At least in Germany, afaik, it is partly a building code thing. Afaik, it counts as a mobile home, so you don’t need permission to build it, even if you never intend to move it.
A lot of rural districts in North America explicitly forbid mobile homes _because_ they don't want people coming in and screwing up the land values and communities with shacks and trailers and temporary houses.
I suspect most of their ordinances also apply to "tiny homes"
Do you have a good concrete example? I'm aware of no location in the US where tiny homes are forbidden or even RVs. Laws can't really dictate what you do with your land aside from public safety concerns.
I vaguely remember few cases where people tried to sic the authorities on a tiny home owner and ended up wasting a bunch of money.
