"The problem is that there shouldn't be a law that makes having two or more roommates illegal. That's asinine."
-That's a matter for the local voters and government to decide unless it's found unconstitutional or opposes a state or federal law.
"Personally, I think that the federal government would have issues with local law enforcement looking in mailboxes without warrants."
-Agreed.
"It may help reduce the problem, but it catches people who aren't going to be a problem, too."
-And if enough of these people are voters, perhaps they can convince enough voters to change or repeal the ordinance.
"Should they ban Hispanic folks from the neighborhood, too?"
-No, that would violate state (perhaps - this is Georgia

) or federal (certainly) law.
-Zeke