Good point, but just to be pedantic, there's a 10% tolerance on the speed, so the actual illegal speed is above 17.1875 mph. Not a lot of people know that!Having reread the thread I get the impression that many of the contributors appear to believe that ebikes have a legal upper speed limit of 15.5mph. Full stop.
As I understand it the limit only applies to the speed at which assistance from the motor should cease. My legal assisted-bike motor cuts out at 15.5mph, I can continue to pedal, my speed rises, I am still riding legally. There is no upper limit to my speed other than the power of my legs. I am puzzled as to how any observer might know whether I am riding a legally or illegally assisted bike. I'm surprised that Pedelec members appear to be confused about this.
As to the wisdom of riding bicycles at higher speed - that's another matter.