That doesn’t mean building a multi level parking garage in that same space is actually a good investment because demand isn’t unlimited. What you see as wasted space can therefore actually be a highly efficient business.

It’s far more profitable to charge people 20$ to use 1/300th of an acre for a few hours than to actually do nothing with it. Which means the opportunity cost to build something is higher.

Unless the building is going to clearly be wildly profitable it may be better to stick with a parking lot.