Someone who owns their own scooter is more likely to know local laws on where not to scoot - and if they don't they can more easily be fined and learn them. Tourists rarely understand local traffic laws and, while you can fine them, they'll leave next week and then a new tourist will arrive that also lacks that knowledge.
So, I'm pretty sure they're talking about the rental-scooters, not all scooters, which, peopel who tend to buy their own don't do these things... but....people get hurt on them, they increase accidents. People do stupid shit, like riding on sidewalks and trying to zip through pedestrians.
they get locked up all over the place, blocking sidewalks, entryways, bikeracks, etc.
in short the rental things are a massive nuisance,
