The UK is full of these in holiday parks, either as homes for middle class retirees downsizing to a nice little community in the country (the economics aren't quite as impressive when you consider the annual charge for the park land and facilities...) or as holiday lodges, including holiday lodges exclusively used as summer/weekend retreats Technically these are all "mobile" but they won't move after delivery.

examples: https://www.tingdene.co.uk/residential-park-homes/our-homes