they dont want people touching the plumbing because of the remote risk of water damage. i lived in student housing at university in a shared unit once, the kind where a maintenance person has access to the space sometimes. i had installed a bidet in the toilet because duh, and they actually removed it and tossed it without saying anything… like its literally not hurting anything but the arbitrary rules say no so fuck me i guess. its just punitive patronizing ass covering of the worst variety. lots of rentals have stipulations that youre not allowed to make improvements at all, but also that if you break the rules and do make improvements youre not allowed to remove them and theyre the property of the landlord… those people are fucking skum sucking leeches who only care about themselves.