Same reason speeding tickets are a thing

I mean, you are sort of making my point for me. We penalize people for speeding, when they are operating a vehicle that has the capacity to speed. We don't require license, registration, and insurance for a 10 year old to drive a go cart around their neighborhood - even if we can imagine a 30 year old modifying it to reach highway speeds.

We don't "need" to have these poorly written laws because of the morons. We need intelligently written laws that will reign in the morons while still allowing new, sensible mobility options to people who want a cheaper and greener way to get around. When we already have the option of intelligently written laws (which other places have adopted and which are already fairly standardized), and then we get poorly written laws, the fault lies with poorly informed (or possibly corrupt) legislators.