Uh, they're poor and probably rough hygenically, which means swing shift is their primary option. Your advice might as well be "be better!". The point is that these aren't all crackheads and crazy people. Also I don't think late jobs are as uncommon as you think they are. I personally wish they had daytime shelters to better serve what I really believe to be the most rehabitable members of the homeless population.

When I worked nights, there were always multiple people who lived out of their cars working with me.