Here in the UK they have never been legal on public land, because the only vehicles allowed on pavements (sidewalks) are those used by the disabled and infants, and they are not legal on roads because they do not have two independent braking systems, as do all legal pedal cycles. Problem solved. Except not quite, because the police are unfortunately not all that keen on enforcement. At least it has kept hire companies from operating here, and if you try to buy one, vendors like Amazon are forced to tell you that they can only be used legally on private land. I'm a little surprised, actually, that the default laws and roads and sidewalks don't apply in other countries and so automatically make scooters illegal.