I think the law puts the ones that do less than 4mph in the same class as kids barbie jeeps, the faster ones should only be used on the road with a warning beacon thing.
Its OK for someone that lives in an area without the problem to pass it off, around here its a major problem, loads of old folk ramming into people or just riding out in front of traffic

People have to dive out of the way or be hit by these nutters on the pavements.
Its her own fault, she should have had insurance, or not use the thing in public.