In my case (where Pennsylvania Department of Labor and Industry provided some funding) I had to be medically evaluated to determine if I was fit enough to stand and ride a Segway. They had cases in the past where people requested a Segway, but did not have either the strength or balance to ride one. My evaluation included strength and balance tests, an evaluation of how it would help me get back to work, and also a demonstration ride for the doctors testing me (Segway i2 provided by the dealer who would eventually sell the machine to the state). So with the need and capability demonstrated, they purchased the i2 for my use (the state still owns it).
The state got a deal because a Segway is 10-20% the cost of an electric wheelchair. I got a mobility device much more usable and suited to my needs.
Given the intensive level of testing and documentation, I think I would be in serious legal trouble if I sold it for something else. I literally had a medical prescription written for me for the Segway. So I guess the same laws would apply.