When I commuted to work and back on my 2015 Haibike Yamaha it could assist above the legal speed cut off.
I only used this ability to ride with assistance at a higher speed riding home from work late at night after my shift on an undulating 10 mile B road route. At the time I was riding there was very little traffic.
I generally averaged 20 mph completing the 10 mile journey in half an hour.
Averaging 20 mph I was not riding the bike as fast as it could possible go, but balancing speed with battery consumption. From memory I consumed 40% of my 400 Wh battery. More in the Winter.
Riding the same route I got to know where I needed to add higher assistance to maintain speeds that would allow me to get home in half an hour at my targeted 20 mph average.
But on the flat, slightly up slightly down sections I used low assist and enjoyed pedalling hard to maintain 20 to 24mph, getting plenty of exercise.
So if you use the gradients and are prepared to pedal hard on a bike that can assist at higher speeds you can actually maintain 20mph plus on low assist. That is what I found.
It would be too complex to ever happen, but the law could be changed to allow unrestricted speeds in low assist and restricted speeds in all the other higher assist levels.
I commuted like this for five years and am still using my original Yamaha 400 Wh battery that still performs very well, so averaging 20 mph for five years did not adversely effect my battery.