in real world tho people find all kind of ways to circle around these things like if they try to cap the rent, then they will just pay in cash or if not then they make a separate contract that the mattress on the floor is worth +200e/month on top of the rent. of course the argument "people will try to break the law" isn't really an argument against why a law wouldn't be good per se, you would argue what if the law always applied. in a world which wasn't a nightmare it would be basically free or a low effort thing to own a home if you want to but if you have a second it would become taxed in ways and if you have multiple ones it would be basically illegal or not worth it. this again would require you can't just find ways to avoid this and pay 0% in taxes by using tricks etc but like i said, that's another discussion.
Finland