This is incorrect - what Fris's neighbor is describing is a Section 8 voucher and it is perfectly legal.
Housing Choice Vouchers Fact Sheet On this page What are housing choice vouchers? Am I eligible? How do I apply? Local preferences and waiting list - what are they and how do they affect me? Housing vouchers - how do they function? The rent subsidy Can I move and continue to receive housing...
www.hud.gov
Anecdotally, I have a former co-worker who has about ~20 units between several duplexes, quads, etc. He has/had a couple of tenants on Section 8 and they've been all or nothing - one put up an above ground pool in his backyard (huge liability issue) and he had to have the sheriffs get it removed, another caused a ton of damage and didn't clean for a year. But he's had several other tenants who, once they had their Section 8 voucher sorted out, never caused any problems and always paid on time (the government was paying over 90% of the rent via the toucher).