Flipping that around, if scooters can't operate safely on the road they should be banned from the road. Which effectively bans scooters and bicycles in any place where there is no bike lane.

The core difference is it's other people that get harmed on sidewalks vs. the scooter rider on roads. I suspect most people are fine with people risking other own lives more than other people.

At the core scooters don't really change that much about transportation vs bikes or simply running. However, they can be really convenient. So, it's going to be interesting to see how things evolve.