Yeah I'm not quite sure why scooters were chosen. ebikes seem better in every way. You can even set them up with throttles so they are no effort. Bike geometry is very stable. I have never fallen off a bike on a road.
Especially comparing folded scooters to bikes. (Yes, there are foldable bikes, but they're still big). Part of the workflow of shared scooters is picking them up for recharge and re-location, and you can fit a lot more scooters in the back of an SUV than you can bikes.
I believe the rental scooters can not be folded. They install a collar around that part to prevent them being folded up and stolen. Or perhaps it's just to reduce any risk of them not being unlocked properly from folded position.