The problem with Liberty is not happiness. Meritocracy is decent for that, and a free worker always helps with faster luxes. The problem is gold, wonder construction and food.
In Liberty you get cheaper policies (makes up long term for 3 culture in cap), happiness (meritocracy) free settler/worker, and faster of them (so technically more production) and production.
Tradition gets food, gold, happiness, culture, production (free monument/aqueduct and wonder production) and defense. Also, food gives you more everything.
So Liberty loses food, gold and defense. Tradition has all of liberty plus more. Also, Hanging Gardens is better than Pyramids.