Yes, 25 km/h (15.5) mph is ridiculous. I can cruise way faster on a normal bike. And the assist to hit 15.5 mph likely cuts out a couple mph earlier, making the real cruise speed lower.
Cars barely have any computer controlled limits for speed or acceleration.
It’s a shame the most popular vehicles in the US (trucks, SUVs) are the least aerodynamic and deadliest to pedestrians and other road users.