Wow. I didn't even know that a city could legally do that. I've never heard of such a thing. In effect, then, they probably end up lowering the value of private land that heretofore may have been able to have partaken in building parking structures. Oooo. That sounds pretty dicey on a lot of levels.
Leaving aside the legalities, let's say the city of Sacramento promises such a thing. The city of West Sacramento isn't part of the agreement, right? So what's to prevent them from permitting a ton of parking structures to increase their own revenue (and eventually reach economic equilibrium)? Those structures wouldn't be in as close proximity, obviously, but if the price is lowered to account for that, I would think people might want to take a short bus ride.
See why hiring a consultant is worth doing? Chicago didn't and they screwed up big time.