The coefficient of restitution is actually a function of the two surfaces that are colliding - not just one.
In the case of drivers it is a golf club and a little steel ball. THe USGA and R&A limits this to 0.83 - a persimmon driver would typically come in around 0.78.
There was a time when there was COR limit on golf balls (golf ball and a big/heavy/hard surface) and it was 0.6. I suspect that this has changed, but I am not sure. Regardless, much of what has happened in golf ball technology is related to achieving high spin at lower effective impact speeds (like short irons) and lower spin of drivers.
Threaded Mode
