Replace "steal" with "call a registered tow company" and you can do exactly that - have someone remove an improperly-placed item from your property. Cities solved the problem of improperly-parked cars by creating the entire "towing" concept.
Police aren't a service for junk removal, they are for holding guns. You hire a moving company to remove junk and you get the police to come hold guns if the junk-leaver threatens to do you harm because of same.
Impounding isn't the same thing as throwing them into a dumpster.
Likewise, unless it is registered as a vehicle (and I doubt these scooters are), impounding probably wouldn't happen, and there is no law against tossing abandoned "garbage" that appears on your property.
Interesting. Precedence will eventually be set and then we'll know.
Police aren't a service for junk removal, they are for holding guns. You hire a moving company to remove junk and you get the police to come hold guns if the junk-leaver threatens to do you harm because of same.