I’m not sure the bike is the accurate comparison target compared to the scooter or car for commuting. Also, I think the main reason they are not so popular is laws. I think there was another article on solar.lowtechmagazine where this was discussed, but from my fuzzy memory, the issue there is not yet a separate category for these kinds of high speed limit, electrical assistance vehicles. You either have to use it like a bike, in which case in many countries you are not allowed to go past a low set speed limit (something like 30 km/h) with elecrical assistance, or you have to register the vehicle to be in the category of motorbikes, in which case you are subject to the same rules, like having a license plate, needing to get your vehicle checked at the garage every year and other things. Maybe try to find the article, it will be better explained.