To be more clear. Depending on the location, those flat parking lots can be pulling in 1+ million per year in profit.
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.
The business has maybe 30 spaces at $20/day. If we assume some people use hourly rates but most use daily lets say each parking space makes $25/day for $750/day. That works out to $273,750 before expenses. To get $1 million you’d need over 100 spaces which is quite a massive plot of land for the downtown core of a city.