In the US, in every state that I'm familiar with, you can register/title/legally drive nearly any vehicle. There are some basic "road worthiness" conditions that have to be met, but they're usually simple and straight-forward, like "vehicle must have a rear view mirror". [1][2][3]

[1] https://dmv.utah.gov/vehicles/rebuilt/specially-constructed

[2] https://tax.utah.gov/forms-pubs/pub-09

[3] https://highwaypatrol.utah.gov/wp-content/uploads/sites/21/2...