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.