I don't live in Europe. My buddy has an ebike that can go 30mph for 30 miles. I see the same model on the bike path at least a few times a week, often at high speed.
The rules are irrelevant to capability.
I do own a European car, it is happy to go 120mph on the highway, even if that's not legal anywhere in my country.
Different ebikes land in different regulatory classifications. Your buddy's "ebike" is legally a moped (US). Class 3 ebikes can only assist up to 28 mph. The people riding that model on bike paths that do not permit mopeds are breaking the law, just as if they rode any other moped on that path.
The rules are irrelevant to capability.
I do own a European car, it is happy to go 120mph on the highway, even if that's not legal anywhere in my country.