ATV weighs 400 lbs and doesn't use off-the-shelf bicycle components.

This is basically a recumbent four-wheel electric light-duty fatbike. It's a niche and I think it's cool.

One could just as easily compare an electric bike to a honda ruckus.

An ATV doesn’t provide the trunk support that most wheelchair users need.

Will modifying an ATV to give trunk support not be cheaper ? it won’t be as portable though

I suppose so. I think that an ATV’s saddle style seating is less stable in general though. I’ve never ridden an ATV but it seems to me like a lot of the time rider stability is derived from the feet being planted and the quads and glutes being able to hold onto the saddle, which for paralyzed users is unlikely. In this vehicle it has an actual seat so the butt stays planted and provides the side-to-side stability.

ATVs are loud and often require use of legs to ride properly.

for price of this vehicle you can buy already electric ATV, so much for noise