Well the arbitrary response time is driven by users requesting rides. If Uber takes that long to match me with a driver, I assume the app is busted and I switch to Lyft.
There could be a law that a driver must have at least one full minute to accept a request. That would help this problem, even if one minute is still a short time to pull over and respond.
Right now enforcement is at, what, 1/1000 rides (to pick an arbitrary number)? If it was 10/1000 would it influence my behavior? I imagine that 10X or even more enforcement would be required, which may not be practicable.