You say that after playing one game? I really hope this isn't true or Liberty is a dead tree.
By the way, in every lets play I've seen so far, tech costs increased by 3% for each city (not 5%). Maybe different game settings?
I did play with Liberty, but you have to be careful, if you expand too quickly you are going to struggle a lot. There's next to no income until you get that first trade route rolling.
Might be due to game speed. On standard it's 5%.
How many additional tiles Shoshone gets when settling new cities?
They get 8 additional tiles.