>What if a neighbor allowed homeless to camp in front of their house?

People keep writing this, obviously, without thinking even for a minute. A neighbor who allowed homeless camp in front of their house would:

1) have to live behind a homeless camp himself

2) be tanking his own house value

3) be open to sanctions from the code as there are way more restrictions on residential property use than there are on commercial.

>When I lived in Houston

Your experience in Houston, where there is no zoning, is not very irrelevant in discussion of zoning, don't you think? Unless you are actually making an example why zoning is important, of course.