Yes, regional.
I cannot imagine this happening in Hawaii or the West Indies or the South Pacific. (feel free to correct me)
Does this "branding" carry over to your dry suits? because they cost a lot! What if a shop said you had to buy their brand of drysuit...is that even reasonable?
Personally, I think it is important to *confuse* yourself a bit about gear, so that you can be familiar with various setups and not be stumped in an emergency.
Actually my first non-neoprene drysuit was because of the dive shop I was affiliated with. It was an OS Nautilus which we got at factory cost back around 1986 I think. I also remember getting my first computer...and for the life of me I can't remember the model name, but it was an Orca and it looked very much like their current Marathon model. It was sold to instructors for 100 dollars. It flooded within the first year I had it.
But in fairness to your statement...I agree that there needs to be clear expectations set before you go to the trouble of getting a DM or Instructor certificate as to what the shop expects. In the OP's case apparently he was told one thing but the end was something else. Personally I would look at maybe another shop if you can't reach an agreement that makes both sides happy if that is an option.