I don't think the FDA should be regulating based on whether or not it's safe to drive while using something.
There are plenty of FDA-approved drugs that should not be taken while operating a motor vehicle.
There are plenty of FDA-approved drugs that should not be taken while operating a motor vehicle.
That said, there is certainly room for an improvement in funding so that the FDA could go through processes more efficiently, but “efficiency” is rarely ever achieved by cost cutting because it confuses cause with effect.
In both cases enforcement is reactive and happens after an accident has already happened.