I think the opening post overstates the public's willingness to put up with measures that significantly alter their quality of life, especially for an extended period of time and for something that is not perceived as life threatening.
Early reports from Wuhan indicated that covid fatality rates may be as high as 10%. That is enough to scare people. As more data became available - and crucially, testing expanded significantly - it became apparent that the overall risk (averaged across all age groups) was more like 1%. But in those first few months when the restrictions were most severe, the 1% figure was not yet known, and we were reading about health care systems being entirely overwhelmed quite quickly in places like Italy and Spain. The perceived threat was, if anything, greater than the actual threat.
I think the fact that there was a conceivable end goal - vaccinations - also helped contribute to people putting up with restrictions even after the lower fatality rates (especially for younger-than-50s) became clear. They were always going to be a temporary thing. The obvious question for climate change mitigation restrictions would be how long would they last? I think there was some optimism that maybe the mRNA vaccinations would be ready in a year, and it turned out to be warranted optimism. If we had got to November and Pfizer and Moderna had said, sorry, our tech just isn't going to work on this virus, I'm not sure how much longer the public would have been willing to put up with restrictions. Why did a lot of people not gather and celebrate the holidays last year? Because they knew vaccines were around the corner, and they could gather for Easter or the 4th of July or next Christmas or whenever. Some point that was far enough out you could understand it. Not 2027.
Even so, restriction fatigue has by and large only increased over time. I would suspect that most of us attended at least one gathering that didn't fully comply with CDC or other local health authority recommendations in 2020. For me, I'm only surprised that I didn't until the fall. But when I did, one of the friends there was a doctor, fully in the know about the risks, but also starved for socialization. In the spring of 2021, I'd attend an event that technically required cheating on the "only attend after two weeks after two doses", since after all, one dose gave 80% protection against Alpha and that was probably enough. And I'm sure a lot of people were ignoring recommendations far more often and far more carelessly than I was.
Now, we've already passed what was pitched as the end goal - vaccinations of significant parts of the populace. I think there's a significant sense of, if I'm fully vaccinated, why should I restrict my lifestyle? We have American football games with 100,000 people in the stadium, very few of whom wear masks, some of whom are surely not vaccinated. Restaurants operate normally. And a lot of people have seen the mental health effects of isolation, and the restorative effects of socializing again post-vaccination. I count myself in this group, and at this point am more than willing to accept some risk of catching covid in exchange for being able to enjoy life with good mental health. I'm not completely careless - I already have received my booster - but with it looking all but inevitable that covid will be around every year like the flu, accepting restrictions to try to contain it no longer makes sense to me.
It's also instructive to travel outside the big cities to see what the reality is on the ground there. I went to a festival in rural Ohio in October; about 0.1% of people were wearing masks, and my group would have been willing to bet money that they had traveled down from the city. Traveling through the Appalachians this fall, outside of college towns, almost no one was wearing masks - and these were the same areas that had below average vaccination rates. In April of 2020, that may have been a different story. But nowadays, life has resumed as normal, other than more people getting sick and going to the hospital and in some cases dying. Still, if you are fully vaccinated, it is really nice to experience life in those areas where things are normal. I'd initially thought my travels would gravitate towards the higher vaccination areas (mostly New England), but found that the areas where everything appeared 100% normal outside of hospitals were the best for vacations - you really could forget about the pandemic for days at a time, and being fully vaccinated, I learned to not care, either.
From what I've read about the bubonic plague, this pandemic fatigue also extends longer-term, with a somewhat fatalistic/live-now-while-you-can attitude setting in. One of the ways this manifested in the 1300s was the marriage rate plummeting, with 25% of English adults not marrying, instead pursuing informal or shorter-term arrangements. Why follow the Church's regulations when you might die in two weeks anyway? There were still aftershock waves of the plague for many decades, albeit not as devastating as the initial wave, but enough to remind people that they couldn't count on the next year as reliably as they had pre-1348. In today's terms, we'd call the result a YOLO attitude. I've noticed this in myself; while I was always very methodical and long-term focused in my life plans before, in the second half of this year my focus has been very much on enjoying life now, without care for building a more secure future. Initially this was motivated by a fear that the Delta variant would result in more restrictions, and wanting to fit in some real life before that happened, but as time went on I realized I was enjoying life with the shorter-term focus more than I had before the pandemic, and that change in lifestyle itself became a motivator for continuing it.
That plague after-effect is an area I want to read more about, notably Barbara Tuchman's A Distant Mirror, which focuses on that time period.
So in summary:
1. There has to be a significant perceived threat to put up with restrictions. Covid-19 met that threshold early on, but less so as time went on and most non-elderly people realized their personal risk was fairly low (partially balanced by risk to older relatives they may be in regular contact with).
2. There is a relatively short time tolerance for lifestyle-altering restrictions. This can vary by populace, but to quote a newspaper article I read recently, even blue states are seeing significant pandemic weariness by this point.
3. Having experienced restrictions once may make people less tolerant of them in the future.
Not that I think it's all hopeless on the climate front. But I think that instead of the type of restrictions seem in 2020, a better approach would be mass investments in infrastructure to support a clean energy transition. Basically a New Deal style investment plan... whether that's the Green New Deal as proposed, or something somewhat different, can be debated. But making huge investments in wind, solar, battery storage, and - crucially - nuclear, could tip the scales significantly. I'm reminded of the Civ4 Edison quote, "We will make electricity so cheap that only the rich will burn candles." Make it the equivalent, "We will make clean energy so cheap that only the rich will burn fossil fuels."
Whether that will happen quickly enough is questionable (perhaps "doubtful" is a better word). But again, I don't see it as all hopeless. In Ohio's capital, voters passed a measure this year that will result in 100% renewable energy by default (opt-out) for all residents - approximately 900,000 people - starting in 2022, and over the next few years local capacity will be built to serve those needs. And while Ohio may not be where you think of first when you think of green energy, the ballot measure was not a particularly close one. If 20 other similarly-sized cities across America did the same thing, it would be a significant step both towards cleaning up the energy grid, and towards establishing economies of scale that would encourage green power grids elsewhere.