Fine the owner (the scooter company) and/or impound it and have them reclaim it (or auction it off if they don't reclaim it). Let the company deal with passing fines through to customers if they improperly abandon it.
But that's easily exploitable: if I see that dickhead neighbour of mine parking up a scooter legally, I can go out there, drag it out a few meters to where it's illegal, and guess who gets the fine? The last user? Wahey!
Or if I have a particular hatred of these scooters, what's stopping me from moving them to be illegally parked and raking up fines? I suppose they'd need constant surveillance (e.g. onboard cameras), but hey, why not, don't we all love our Ring doorbells? /s
Or they'd need to have designated closed off areas to park them, and maybe attendants. Maybe they could get away with something like bike locks using public bike parking spaces. In any case, how to avoid fines for abandoning property all over the city should be their problem.
Yes, I agree. And I think the obvious outcome is that the fines would be unavoidable, in that the solutions would be financially prohibitive. Thus, scooters would be effectively banned from the city.
The scooter vendor here, Bird, requires that the rider snaps a photo of the scooter as it is parked after any given ride. This assures the company that the scooter was parked properly, and it tends to indemnify the rider against later claims that it was not.