Which I guess is part of the point - the rule specifically does not say anything about use, only presence - but people (including me) are still interpreting the rule with a "usage" axis. Perfect demonstration that the "simple rules for Internet content that are easy to apply" assertion has fallen over at the first hurdle.
I think, just being overly annoying and literal, that the game shouldn't be answered by asking whether anyone would call a wheelchair a vehicle, but whether a wheelchair is a vehicle in the sense meant in the rule statement. I don't think it is, personally, though it's probably the closest non-vehicle in the list.
Strictly speaking, by the definition of "would anyone call this object a vehicle", every single thing on the list is a vehicle, because apparently at least ~2% of the quiz respondents said they were vehicles - including kites!
After all, bicycles are clearly vehicles, and bicycles and wheelchairs are both things with metal frames, wheels and seats designed to convey humans around under their own power.
Other than the placement of the wheels, the main difference is the character of its use.