When I bought my bike off of someone was interesting. This was the first time riding a motorized bike.
I already knew how it worked, and he just gave a quick rundown of the bike. he had it set up funky so the left hand brake was activated by squeezing with your thumb. Anyway, I got on and took off. Went round the corner and tried to stop but A) the brakes were just sucky, and B) that wonky left brake threw me for a loop. I got stopped, but I almost ran into a parked car, and I stalled the bike. Started it back up, rode back, told him I'd take it. Took it home, flipped the brake around, adjusted the brakes, and it was great.
I could see how someone might have trouble learning to ride one, but for most people it shouldn't take too long. after 4 hours not being able to do it....I think someone's looking out for that person
Honestly though, I think if you're unable to ride one of these because of something other than balance, you probably shouldn't even be driving a car...cars are just as complicated, if not more due to distractions like your phone or radio and whatnot.