I don't think the devil is in the detail with driver seatbelts, but the overall picture; they improve matters for drivers to a degree we're not sure of because risk compensation, but make matters worse for everybody outside the car because risk compensation. Motoring is a highly efficient way to externalise one's costs on other people anyway; less of that would be good.

This can be a controversial subject, but... helmets ain't even a tradeoff - for whatever reason, the things appear to do approximately nothing.