That said I have no problem thinking C cards can be bought based on the many "certified" divers I've met in Cozumel who were very lucky to have DM's & boat captains set up their gear etc.
I can't remember a course I took that didn't have the bookwork and actual in-water tests required, other than my Nitrox course but it still had a written test. All my courses were taken in the early 1990's except for the Nitrox which was taken a couple years ago. I really do think that the major dive organizations are selling C-cards, especially on the beginner end of scuba diving. After all, they have a very large industry they need to keep feeding. I think they know that the number of people that take an open water course and then continue diving is probably relatively small with maybe one trip before retiring their C-card. Most because they don't like (or won't) travel alone and/or don't have a LDS that travels other than maybe one trip per year.
The majority of my diving has been done on live-a-board boats in conditions that were at times pretty extreme, far more extreme than what I have observed from the El Norte's that closed the port in Cozumel. I've never been on a live-a-board that "closed the port" (so to speak). There are no DM's in the water guiding you, just a simple briefing and you (plus your buddy) are on your own, day and night. Then I read the stories of diving in the North Atlantic and read what they go through and I consider myself and my dive experience as woosy. My hats off to all the tech divers, not my cup of tea but I understand the desire, prep and training that goes along with it.
It isn't the size of the boats either as I've been on live-a-board's where the hang tank appeared and disappeared with the roll of each swell. It made the safety stop almost worthless. Or when you did finally reach the ladder it was worse than riding the bull at Gillies (that should date me).
It has only been the last few years that I've started visiting land-based resorts. I've been amazed at what I've observed. I've often thought that each time they closed the port in Cozumel they have probably saved quite a few lives by doing so. I think they know that if the conditions aren't almost perfect they would be in real trouble letting the boats go out. I'm actually surprised that there aren't more fatalities from the little I have observed (not talking about the DM's or dive ops).
Watching people show up for their check out dive dragging their dive consoles behind them (on the concrete) and then struggling for an hour or so to get their gear set up, scratching their heads and not having a clue. It's really scary. I'm sure the stories we could share would send shivers through our tanks.
And I cringe at the people that want others to handle, take care of and set up their gear. If they ever got in trouble they wouldn't have a clue what was causing the problem. IMHO concierge/valet diving should be banned from all resorts and dive ops.
Just my two cents..