You can't buy a car unless you have proof you have a parking spot, so the cars part is out. Same deal with RVs. No street parking, no RV.
There's no space for people to have a horse.
There's plenty of places that I think everyone would call a "shack" made from old tin that's probably been around since the 50s or so, and is not really any different from a mobile home. So that exists here and people are generally OK with it.
People wouldn't disconnect from the sewer to do septic. That isn't a zoning issue, it's a public health one, and it's obviously illegal.
Honestly, none of the hypotheticals described have to do with zoning. Social pressure to do the right thing is a thing here, but not the only reason that things aren't super chaotic.