Regular non-motorized bikes can go 20+ MPH on flat ground. Also good to point out that there's a difference between e-bikes and e-motos. An e-bike is just pedal-assist, won't go without pedaling and is generally speed throttled pretty low. An e-moto is for all intents and purposes an electric moped / motorcycle (Some of them have do-nothing pedals to disguise this fact) and should probably be kept away from children in most contexts. But nothing is wrong with any of these vehicles so long the jurisdiction has sensible licensing rules and public outreach concerning the last category. The rest of the vehicular laws are already there. Ultimately the problem of e-motos is one of governments having to get off their ass and formally recognize them.