It's a problem that popped up with GnK. In vanilla, mercantile AI was always able to bribe all city states in the world making your life miserable. Before spies and complicated missions, it was the only way to accomplish anything with city states and AI was always willing to use it. Since GnK they totally don't care. It's a grievous bug that hasn't been fixed yet. I understand that not all civs must always go for each and every city state but when there is an "infrastructure project in progress", AI should be able to use 2-3k gold (10% of their savings) to secure its domination.