Safer scooters

I've been thinking about the number of injuries turning up everywhere from those electric hire scooters which I am tempted to try.  (See here, for example.)

Having watched people on them (and some videos of people going all wobbly on them - you can search Youtube yourself), I reckon that part of the problem is that they do seem to need more of a sense of balance than they should. 

Hence:   why not have a three wheel design?   They exist:

or this:

Surely these are better from a balance point of view?   Surely the additional cost of an extra wheel is worth a safety increase?

I'd be tempted to legislate this, if I were in charge.