I had a shoulder op earlier this year and was told 2-3 weeks by the surgeon, but if I did all the physio exercises, used the ice to reduce inflammation it could be earlier if I felt up to it.
I had a follow up physio appointment two weeks after the op and was given the all clear.
I was told they err on the side of caution, as some patients don't follow the recovery instructions. Whilst they aren't concerned that you might damage the shoulder, if you were in an emergency situation, you might not have the strength or feel sudden pain taking avoiding actions and might be considered partly to fault by insurance. Hence I waited until I got the all clear by the physio, even though I had felt fine to drive for at least a week.