In my (relatively light) understanding, Japan in general doesn't really do selective enforcement. If they see you riding a scooter without a license plate they'll pull you over right away.
You even need a registration for your bike in Japan. As a foreigner you would be randomly pulled over to be checked. As for scooters, this is such a different way/level of experience than walking. They cant be compared. Personally I when using a scooter i’m more looking out for potholes than seeing anything of the city. Walking is so much slower and allows you to make meaningful connections also with the inhabitants of a place (even pickpockets ;)
Right, but these public e-scooters (like Bird, Lime, etc) all have license plates by default --- and that's why they generally won't pull you over unless you are breaking traffic rules. By all means, if it doesn't have a license plate at all I think you'd get pulled over in Germany also.