FHA and HUD loans cap the ratio of commercial to residential, and so strongly favor single use developments. Banks take their cue from this and are also less willing to lend to such projects. It's a shame because in many cities, these are the most vibrant neighborhoods that are definitely commercially viable, though maybe not as lucrative much as a mall or exclusive condo. https://www.strongtowns.org/journal/2016/2/12/roadblock-on-m...