If only it were a legal vehicle in more places (with four wheels, they'll need to get laws changed on the definition of a bicycle in order to use that on public paths/roads/etc. in at least much of the USA, and possibly elsewhere in the world. Almost everywhere I can think of, bicycle-class vehicles are required to have three wheels or less (in contact with the ground in some laws), as part of their definition, so to be usable on public roads/sidewalks/etc. in those places this thing either has to lose a wheel, or it's makers have to get the laws changed.).
That last part might be possible, but it is also likely that lawmakers would change other things about the law while they're at it, just because they can, that would make other vehicles that are presently bicycle-class no longer so.
At present, for example, here in AZ (and many other states) that thing is not a legally-defined vehicle of any type, so it wouldn't technically be allowed on any public ways. Whether or not that gets enforced would be a whole other thing, but if they chose to enforce it anyone riding one would be screwed.
(this is why my SB Cruiser is a trike, not a quad, because I could do a lot more with it if it was a quad, with more cargo room up front, or a dog carrier front and back, and not need a trailer for most things, but if law enforcement decided to pick on me they would be able to based on it having too many wheels....at present it's just a bicycle, under all the AZ rules for such things).
Personally I think the laws about how many wheels something can have are just dumb, but it's not uncommon to define things that are not motor vehicles (cars, trucks, etc) as having "no more than three wheels in contact with the ground", so having more than that makes them something other than a defined type of vehicle, which means law enforcement might try to insist they are then one of the other defined types but not qualifying as legal because they dont' have all of the other requirements.
(this is what they do when you exceed 20MPH on an assisted bike here in AZ, for instance--since <20MPH is part of the definition of an assisted bicycle here, then they say that you must instead be an unregistered, uninsured, unlicensed motorcycle, and since it doens't have all the DOT required stuff then it's illegal for that reason, too).
Stupid bureacracy.....
