"Give someone a ride, let them borrow your car, let them stay over at your house while they're on vacatin, have a one night stand with them. Nobody thinks we need government regulations for this stuff. What is it about commerce that scares us so much?"
The things you described are usually just one off things, that a friend will occasionally do for another friend. Once you commercialize it, then it starts getting abused. Take AirBnB: You now have a lot of buildings becoming unofficial hotels. Not only are they driving out regular, long term tenants, but the people who are there did not sign up to live near a hotel.
I think what you're describing is a subset of the character of your neighborhood changing in a way you don't like. For example, your neighborhood becomes expensive, or gentrified, or crime filled or you don't like the noisy guy who moves in upstairs from the apartment you're living in. Or the deli you like downstairs closes and is replaced by a hair salon and you didn't sign up for that. These are problems that are part of life, you can't control everything outside of what you own. I wouldn't personally expect to legislate it any more than if my gf broke up with me because of Tinder or FB or something its just life.
The things you described are usually just one off things, that a friend will occasionally do for another friend. Once you commercialize it, then it starts getting abused. Take AirBnB: You now have a lot of buildings becoming unofficial hotels. Not only are they driving out regular, long term tenants, but the people who are there did not sign up to live near a hotel.