My dad is landlord of an 8-plex in a small town. My brother is a social worker in a big city. When they get together and talk it's amazing how much their jobs overlap. So much of the job as a small time landlord these days is dealing with drug abuse, interpersonal problems, police, social services, housing authorities, etc.
Around the time we bought our place we had some spare cash and thought about getting another house. I'd seen the Rich Dad, Poor Dad book which had the advice that you should buy a rental property only it was wildly cashflow positive after the mortgage.
That's not realistic in most cases but we saw one rental property which looked crazy profitable that was full of Section 8 tenants. We passed on it because it was really buying yourself a job as a social worker and the fact that we were bleeding hearts would make it harder, not easier. I think my wife and I have gained the maturity that we might be able to handle that now but we've also gotten better at setting boundaries such that we wouldn't.
In section 8 a few bad tenants strip everything of value to hawk for drugs. Sure the rent is paid but now the city is up your ass for code violations when the very people that destroyed the place complain it isn't habitable. Which you must now repair so it can be stolen again.
That's a result of the market your dad is in. Vast numbers of renters and landlords are just ordinary people with no/not dealing with drug or social problems.