If you look at the videos of delivery riders, you'll see that the majority look decidedly foreign, and it has been proven that some of the migrants staying in hotels are operating illegally as delivery riders. I personally don't have any proof, but a little birdie told me that there are gangmasters who provide the ebikes for these guys, and they charge rent on them. The riders themselves know nothing about the bikes, the laws or anything like that. I'm not saying all delivery riders are illegal immigrants. I know that many aren't. I have no information on the numbers, but from what I have seen, what the little birdie told me fits nicely for a lot of them.
Since the police have started cracking down, I've noticed that the big pancake motors seen at the migrant hotels have been mainly replaced with geared motors. As you know, it's now possible to buy "250w" bikes with motors and labels indicating 250w, that appear to have the same motors as others marked 500w or 750w, the same as on a couple of my bikes. Anyway, it's not the power that matters. It's the speed. The point is that the gig economy is very dark. A lot of dodgy things happen in it.
I'm pretty sure that the majority of delivery riders are not in a position to get a licensed moped, whether it's because of their immigration status or the affordability, but what prevents it most is the traceability through the licence plate. The license plate would solve a lot in terms of regulation, but the industry would temporarily collapse because none of the riders don't want to be regulated or it's not viable for them to be regulated.
The police are starting to deal with the illegal high speed of the delivery bikes and theye're restricting them in pedestrian areas, but that still leaves a lot that regulation could improve.