It can't be perfectly harmless if it is ruining someone's experience. Its kind of like urinating in public...maybe it doesn't hurt anyone but it sure does ruin a lot of people's experience...and thus it is criminalized.

If there were more public toilets, there'd be fewer public urination. The law is there to catch the few that do it.

But if there's tonnes of public urination because there are no public toilets, then even tho the law says no, people are still going to do it. There's a demand to pee that cannot be stopped.

The idea that airbnb should be outlawed is irrelevant - the fact is that there's demand for it. This means there's a lack of short term rentals in the area. The demand must be satisfied, and so the price of it grows.