Of course, if you slip in the grass and injure yourself the driver may be in bother.
What few folk appreciwte is that you don't need to physically collide with someone to be responsible for an injury. Your motor vehicle needs only be present on a road or other public place. If Accy walked round on the wet grass, slipped and broke his hip (and assuming I were still a copper) I'd book that van on as Vehicle (1).
The classic example is a vehicle that parks on a blind curve that forces drivers blindly into incoming traffic. The vehicle may not physically be touched at all, but its presence on a road is responsible for the resulting head on collision. Known similar get to court a couple of times over my 3 decades, including a blind man that fell and injured himself because some tool revving a stationary motorbike nearby gave the poor old feller the impression the bike was coming straight at him.