I'm not a SCUBA instructor, but I am/was a PSIA ski instructor and an NRA pistol instructor. Locally, I was comped for lift tickets if I showed my credentials and home area seasons pass. Out of the area, if I asked nicely at the instructors admin office, I was generally comped a lift ticket - but if I hadn't been, I certainly wouldn't have kicked up a fuss.
As an NRA instructor, I organized several two-day advance training courses with a visiting, high-caliber instructor. I organized the class, secured the training venue, and took care of the instructors local needs. For that, I was provided free training in the course, which was quite a fair trade, I thought.
I'd never criticize a shop or resort for not giving the proper "entitlements" - comps are a courtesy, not an obligation.