Alice doesn't want to build it because if she doesn't she can afford to build twice as many housing units on the same lot, which is worth more money even without parking spaces, and the building doesn't need such an expensive foundation if it doesn't have to support a multi-story parking structure in addition to the housing units.

Bob wants to build it on the next lot over once he sees these new buildings going up and is willing to bet that the new residents will generate demand for parking, and can choose how many stories to make it based on the local demand for parking, which is based on numerous hyper-local conditions that are best evaluated by the owner of that specific lot and not just based on how many housing units are in each building.

> No one is prohibiting Alice from building the 10-story parking structure. The change is she's no longer required to build it.

Alice is a smart capitalist and will build two apartment buildings instead, maximizing profit from selling the units.

By the time the buildings are completed, the mortgages signed and the people start moving in and fighting for parking, Alice is long gone, moved on to the next project in some other city.

This is the problem parking minimums were intended to help reduce.