While I am not surprised that clearly- unbiased source, "reason.com" calls this an example of runaway nanny-state regulation, the fact remains that millions use the sidewalks of NYC every single day, and those people have the right to safety.
Digging a bit deeper into the question of their legality, we find this article from the NY Daile News
It appears that these motorized electric scooters - which I've personally only recently become aware of, and until reading this article had no idea they were becoming so popular, essentially fall under a broad "motorized transport" classification.
I guess that it is easy to paint a picture of "big government wants its pound of flesh" surrounding their registration. However, the interpretation I take is that any tom, dick, or harry can't just go driving a motor-propelled vehicle on the streets and sidewalks of NYC. In fact, the whole topic of this thread is that 15,000 of these things are siezed in the UK for being unsafe. Are the scooters being sold on the streets of NYC coming from a different chinese factory? Is there any less of a problem of bootleg, unsafe goods?
I'm sorry, but I'f I'm walking down the streets of brooklyn or wherever, I don't want someone slamming into me on their unsafe, unregulated, apparently-on-flames motorized fad-scooter.
But you're right, government only exists to regulate, regulate, regulate. It's all just rules and red tape, isn't it?