In the U.K. out of london the vast majority of vehicles on sidewalks are cars. They are explicitly banned from driving on them except to enter adjacent property, yet nothing is ever done, and dozens are killed every year by those drivers.

There's scooters and scooters. It's a bit of a misnomer but there are electric scooters that are like a Vespa scooter ('Absolute beginners') and there are electric scooters that are the ones that your kid would ride when they're 5 or so (plank with two wheels, you stand on the plank and 'scoot' with your other leg). The e-scooter of the latter variety is what is of concern here, ~20kg + rider moving at ~20kph (sometimes faster).

The former is definitely banned from sidewalks (though they are often parked there), the other is used on sidewalks quite frequently, in spite of that not being legal. They have shitty small wheels and are pretty dangerous for both rider and pedestrians.