When I first began, it was with the YMCA, and they provided everything, including masks (no snorkels, if I recall, were ever used in that OW class) -- the only exception being the wetsuits, which we had to rent or buy, for the ocean dives. Pool sessions only required swim trunks.
The regulators were a mixed bunch, chosen at random from an old plastic laundry basket. What was unique back then was that there was never any sales pitch when it came to eventually buying your own gear, since the "Y" was never directly associated with any shop.
Fast forward a few decades, now with alphabet-soup agencies and sectarianism, up the wazoo, I ran into a college instructor -- presumably some GUE cultist -- who wished to argue with me about the safety of my niece's upstream regulators, which she received for high school graduation.
Crap, so much has become increasingly granular in recent years. I never thought I would ever have to justify a regulator design, to some CSU twit, with a massive hog ring in his nose . . .