> That's the difference between a motorcycle and an e-bike, not speed.

Not legally.

I would argue that the presence of pedals matters much less than the power and weight of the device when it comes to how it should be regulated. Power and weight are what create the risks that the laws exist to regulate.

If you have an ~80 pound device with hardware that can do >40mph on flat ground, it should not regulated like a bicycle.

Edit: To make my point clearer, I think the focus on top speed in a bit of a red herring. High speeds can be achieved on anything with enough hill/drafting/etc. The rate at which the object can gain kinetic energy is what matters. Devices that gain kinetic energy quickly are much more dangerous to operate. Thus the combination of Power x Weight is what the regulations should focus on. There is such a plethora and proliferation of different device types, any other type of distinction can't keep up and will either leave safety gaps or unnecessarily curtail critical innovation in personal transport technology.