I believe the Autobahn still carries the legal requirement to drive at a safe speed at all times. Pedal to the floor racing is not often safe speeds for a public road.
I mean, every person who purchases a car does so, at least implicitly. The very act of obtaining a driving license contains an (often explicit) promise to abide by the rules of the road.
You’re conflating two things and ignoring the thrust of the point: nobody buys a fast car to drive it slowly. Maybe some people do, the vast majority do not.
If promises about licenses meant a damn, we wouldn’t have speeding cameras.