If it's just a few, that's not a big deal. But what a lot of people are envisioning isn't just a few scooters and bikes left around, it's the nuisance and eyeso

If it's just a few, that's not a big deal. But what a lot of people are envisioning isn't just a few scooters and bikes left around, it's the nuisance and eyesore of public areas being absolutely littered with these things that people are seeing in photos from cities that have had these services for a while. I don't think they're wrong. I also don't think it's a non-solvable problem. It seems that the worst of it is largely due to there being simply too many of the things -- far more than are needed to actually meet the demand for short- to medium-distance transportation -- in many cities. Requiring companies to get a permit for each of their bikes so that the city has a way to limit the total volume, and so that it can ensure that the rollout happens incrementally so any apparent problems can be addressed before they create a major nuisance, would probably be more than sufficient.