This seems like something really fun. HOwever I would think that besides the cost, its a two wheeler and subject to the same dangers of a wheel losing traction on a slippery road and getting into a crash just like a regular big bike. And the trainer wheels wouldnt be able to do you any good.
It looks to me that the original video is a bit old. You can tell because the presenter Jeremy Clarkson is wearing 80s style clothing and sporting a mullet hair cut.
The training wheels might not stop you crashing but a crash would be a lot more survivable than on a motorcycle. Clarkson’s wearing a seatbelt as well as a mullet.
Thinks: If you stretched the wheelbase of a scooter a bit (I THINK the midframe is usually just a single large diameter tube) sat on (or just above) the floor, maybe lowered the steering column and bars a bit, and (optionally) added a roof (which if load bearing would make the whole thing a lot stronger) you’d pretty much have a one-off Quasar-scooter.
Edit: (Except it wouldn’t have a 4-cylinder 850cc shaft drive engine.)
BUT as mass-transport maybe it ain’t gonna happen anytime soon.
Gyro-car, two wheels, 1912! (prototype, apparently didn’t corner very well)
Maybe they should have the trainer wheels retract ONLY after 100kph?? Then it may be safe enough? Because after 100kph you really wont be on a regular road anyhows?