Well, I've never been turned down (never dived in Northern America btw) but I remember some places when the operator was relieved when I showed both my PADI and CMAS certification because he knew only one and not the other, all depending on the location.
Alas, I must admit my homeland (France) is not really PADI friendly. I remember diving with a friend, she had been a diving instructor for at least 2 decades, for various agencies, PADI among them. We were with common diving friends, and had planned to dive the 'Grec' and 'Donator' (wrecks between 40 and 56 m) in le Var. I had organised everything and I knew the manager, I had given him the background of all divers in the group, everything was ok... Until we got on the boat. That instructor came to my friend and told her : you don't dive unless an instructor accompanies you ! We sorted it out, but it took some time...
That was 10 years ago, situation has improved, but is still far from perfect...
Alas, I must admit my homeland (France) is not really PADI friendly. I remember diving with a friend, she had been a diving instructor for at least 2 decades, for various agencies, PADI among them. We were with common diving friends, and had planned to dive the 'Grec' and 'Donator' (wrecks between 40 and 56 m) in le Var. I had organised everything and I knew the manager, I had given him the background of all divers in the group, everything was ok... Until we got on the boat. That instructor came to my friend and told her : you don't dive unless an instructor accompanies you ! We sorted it out, but it took some time...
That was 10 years ago, situation has improved, but is still far from perfect...