Small motor assisted bicycles

A hundred feet from my front door a rider of one of these was struck by a car and I saw the police and EMS response. Later I saw a few more of these bicycles. They don't have license plates. At this point I don't know if they are required. However, I saw that the riders in the street simply aren't aware of the cars around them and how slow they are travelling relative to the other traffic. I prayed for the person on the ambulance gurney. Maybe I haven't been paying attention but they just seemed to have appeared in September in Queens.