That's for regular apartments. The blog author went to a monthly mansion, which are used for holiday rentals and other short-duration stays of a few months or so (such as people moving to a new city and needing a place before they can find a permanent apartment, or maybe people on temporary work assignments in a new city).

They do. But lots of people buy homes just to rent them out. That removes a home from the market, and the competition pushes prices up.

The problem isn't signage.

Plus evicting/canceling a contract is an arduous process. It almost always favors the renter. And in the case of actually buying a home, there isn't much anyone can do.