I saw one for rent on Facebook Marketplace not to long ago.
A nice campground we used to frequent up near Tower City PA had so many permanent residents that they had few full-hookup sites ever available for transients. And they had a yearly rate too.... Obviously, the zoning rules vary a lot from place to place.
Very true, it depends on the community and what people want, sometimes it's what developers want because they have lawyers that sue.
If it's a true rural area where camping is an industry, I'm sure they are more receptive and the regulations are only there to protect the environment (and customer) from sleazy landlords (basic health and safety).
In more populous areas the concerns tend to run to impact on the neighbors, if a fire starts, you obviously want to knock it down before it damages more homes. But then there is community aesthetics. In the burbs people are very protective of their property values. Hence you have laws and HOAs regulate appearances. Nobody wants to buy a home next to a shithole. So while someone might want to live in one, it has the potential to be a health, safety and economic problem for their neighbors.
From what I've seen of the designs of Tiny Houses they are also geared to be eco-friendly, which typically means they have a compacting toilet, don't require a sanitary hookup, but probably a need for potable water and electric. Which to me sounds more like an RV even though they are build / meant to be used year round as a permanent residence - at least that's how they are marketed.