Comment by fwlr

What was your answer on the wheelchair? Same as for bicycle, or different? If different, what about a wheelchair but the person in it doesn’t need a wheelchair, they just enjoy the sporting aspect of arm-powered vehicles?

The other way I would “problematize” (to borrow the author’s wording) your crystal-clear understanding is to ask about the matchbox car, then the remote control car, then one of those kid-size toy cars that the kid drives around (then a small one-person electric car, then a full-size electric car).

I suppose another angle would be, are bicycles okay? What about battery-powered bicycles? Does it change if we add a small petrol motor to recharge the battery?