Under Realistic Corporations, they self-found under certain conditions.
I hate it.
The whole point of these things is they are the equivalent of religions for non-prophet GPs to found and it makes the strategic choices to collect the right types of specialists a critical element of the game from the very outset, whether to spend certain ones or save them for this inevitable need...
Anyhow, someone prior to C2C thought Realistic Corps would be a cool option and I wouldn't remove it but I don't advise it.
Corps require being placed where you can maximize your gold% modifier in that city so you can make the most out of the flat rate gold you get per city that adopts the corporation enough to counter and exceed (in most cases) the expense of operating the corporation in those cities, at least when it's your own cities - it's going to just be an expense if you can get them out to opponent cities but of course there are HUGE benefits to most corporations in trade for all that gold operational expenses as well. But when you get the corp founding in a random city, you can't hope to have your world and national wonders there to maximize the income per city and if you don't do that, they can really destroy your economy.
You MIGHT be able to get away with using worldbuilder to remove Realistic Corporations. Keep in mind there's also another option for additional corporations, and those are cool.