Why do so many electric scooters and bikes end up in city rivers?

In Paris, a startup called Guppy is on a mission to relieve the river of the many rusting vehicles lurking on its bed by groups of volunteers using magnetic fishing rods. — Guppy/dpa

Few can disagree: Electric scooters and bikes are a far more environmentally friendly way of getting around a city than cars. So why is it that rental bikes and electric scooters keep ending up in inner-city rivers around the world?

It's not only a problem for the rental companies, but also for the environment.