Lot set backs are frequently a part of the fire codes. They help prevent a fire in one building taking out the entire block.

Parking minimums are a chicken and egg problem. My suburb has started allowing new apartments to build about half the parking that would have been required a decade ago. Trouble is, those tenants still own cars since the transit system isn't robust enough to go without. Now those cars flood the streets of the single family residences nearby. Eliminating parking minimums has been mostly successful in the city core but expanding it out to the entire metro doesn't work with how we've built America over the last 70 years.

Many cities have reduced or done away with the parking minimums. It ends up being another way of extracting value out of the existing market, but does little to reduce the median price of new homes.