Averaging 20 mph over non trivial distances puts you in elite territory. Most people can't sustain that, even experienced cyclists. Wind and climbing eats into sustainable speed even more.
Probably. I've never owned a road bike so I was leaving room for the possibility that I don't know everything. (I have ridden thousands of kilometres per year in most of the last ~15 years, mostly urban or suburban, and I have considered myself fairly fit for most of those years. But who am I to tell what other people reach on lighter equipment?)
Whether those in the higher category are e-bikes is a matter of definitions, not legality.
In Europe, this means you need at least a helmet and approved gloves when riding the faster bikes. They're legally considered a form of "motorcycle", so have the requirements: license + registration + insurance. Although, in practice, for smaller bikes, basically everyone already has the license.
That is, again, at least where I live. Last time I took a glance, I got the impression there wasn't EU-wide consistent regulation on that.
Maintaining 20-30 mph on even land takes enough effort, except perhaps on a road bike, that I doubt most commuters or utility cyclists regularly ride at those speeds for length, let alone in urban environments. A fit road cyclist will probably reach those speeds, of course, but I don't think that's what the author contrasted e-bikes with.
The article does seem perhaps a bit weird and the title is clickbaity but I can see how an e-bike at those speeds could be a bit of an inbetweener.
It's probably worth noting that if there's anything the article is probably quite right about, it's the relatively ambiguity of the entire concept of the e-bike. In many jurisdictions at least in Europe, e-bikes are legally limited in terms of powered speed (25 km/h where I live -- you can ride faster but the motor can't give power beyond that). In some jurisdictions they don't seem to be legally limited at all. There's a big difference between a bike that runs at normal commuter/utility bicycle speeds but helps you do that and what is essentially an electric moped.