It's more the power that can be applied. Most people capable of getting a pedal bike up to those speeds also know how to read the road for safety. Even then, bikes can basically disintegrate in a (initially) minor accident.
A powered bike is capable of destroying itself if misused.
I thought they put it in, but accidentally reversed the sign. Instead of slowing, they actively accelerated.
It was back when it was a street racing game. The idea was that cops would box you in, and slow you down.