You most definitely should not be buying rental property without familiarizing yourself with the local rental laws. That's simply awful, awful business.
I don't feel a lot of sympathy for the landlords in SF. If they want to own property that isn't rent controlled, there's a whole big country out there, the vast majority of which isn't rent controlled. They chose to buy under the restrictions that exist. That's their responsibility.
It doesn't take long to learn the basic laws about something that are most likely to affect you. And then consult a lawyer for anything you are not sure about.
>If I wanted to rent my apartment out I wouldn't go searching for laws...
This is a dangerous level of ignorance.
When you rent a space that you own to another for residential use, you forfeit the vast majority of your privileges as a property owner. Pretty much every jurisdiction recognizes that a person requires a secure space to come home to in order to have a chance at a decent life.
If you're thinking about renting out your property, you're setting yourself up to be royally fucked if you don't familiarize yourself with the relevant laws.
"A bit" is an understatement. You're incredibly, dangerously ignorant. Yes, I know, that sounds harsh, but "doing your homework" is a necessary precondition for doing, well... anything.
If I wanted to rent my apartment out I wouldn't go searching for laws--I'd go searching for tenants (and a basic lease agreement I could modify).
If there's a required course or something, I guess it would make sense then.