50cc category is important in Japan because it's really easy and cheap to get license, and some high school students are allowed only to get 50cc license.
It will be interesting to see how this affects the 50cc and below vehicle class, which require helmets, have a speed limit of 30kph (somewhat enforced, often broken) and are required to make a two-step right turn on larger junctions.
It might be good timing to re-assess the rules for 50cc vehicles. Driving at 30kph while traffic is going past you at double the speed is more dangerous than moving with traffic. Differential speed limits have been shown to be unsafe and modern 50cc scooters can keep up with all but the fastest city traffic.
30km/h at the crest can easily turn into 60+ km/h at the bottom if it's steep.
But basically with light driver this isn't too hard enforcement.