OK, but do not these places have those fecal collection bag dispensers (with a bin, of course) for dogs? We do, it is emptied on a daily basis. Homeless people actually use it, apart from going to a homeless shelter which is another option.
I think it's a matter of local culture so to speak. I can see a different attitude in different cities and a 50/50 between "I am not using a dog bag, I am not a dog" and "I'll do what I can not make a mess on the street".
See the remarks about de-institutionalization and the insane.