(otherwise known widely as trailers or mobile homes, but trailer parks already get a bad rap despite largely being the last few examples of affordable housing in the U.S.).
Trailer parks get a bad rap in part because they're usually incredibly abusive. You own the mobile home, but you don't own the land it sits on. You pay rent for the right to have your home there, and that means that you can get stuck with enormous rent increases. Even though mobile homes are technically mobile, moving one is expensive enough that people have a very hard time doing so once it's installed somewhere. That means that if the owner of the trailer park raises rent past what you can pay, you can end up losing the house that you own, because you can't afford to move it.