I just discovered this thread and I skimmed it rather rapidly, so forgive me if I say things that have already been beaten half to death.
I should start by disclosing my prejudices. I have a very low opinion of scuba certification courses. When I bought my first tank and regulator in 1954 at age 15, I had been freedive spearfishing on a fairly serious basis for a couple of years. There were no certification courses available. I read The Silent World and the small manual that came from US Divers and put on my gear, grabbed my speargun, and went spearfishing. The manual told me not to hold my breath on ascent.
I'm not recommending this as a way to learn to dive, but I survived it. Later, as a Lt. in the USMC, I went through a month-long US Navy scuba course that was very rigorous, and actually flunked people out of the course. Fancy that!
I was stationed in Hawaii at the time, and met my wife there and taught her to dive as a prerequisite to marriage. She was a very competent diver, partly because she was a very strong swimmer and comfortable in the water.
Later, we moved to California just as certification became standard fare. Dive shops would refuse to fill my tanks because I didn't have a NAUI card. A US Navy course was apparently not good enough. Coincidentally, every dive shop that refused to fill my tanks also happened to offer a certification course, and I only had to pay my money to get right with God.
Around the same time, I literally had to save the lives of a couple of certified divers. Does it begin to sound like I'm a cynic? Its true.
My wife is a rule follower, and she always felt bad that she wasn't certified, so I agreed that she should go through a NAUI course. I watched her class get its final pool session before going in the ocean, and it was pathetic. One requirement was to swim around the margins of the pool on the surface with tank on your back, breathing though a snorkel. I can't recall how many laps of the pool were required, but she was the only one who completed them without grabbing the side of the pool to rest and/or cutting across the middle. But every single student passed and went on to his or her first ocean dive. I almost refused to let my wife be in the water with them. Every student passed the course too.
My 12-year-old son was next to get a NAUI card, and it went the same way with his class.
OK, there is my history of cynicism. Now let me state the one problem I see with certification courses. I am not familiar with some of the foreign programs, but all that I know of in the US have a basic conflict of interest. The dive shop offering the course has an interest in passing the students for two reasons.
First, if the word gets around that students actually fail, then students will just go to their competitors.
Second, and maybe more important, the dive shop wants to sell equipment to the students when they are certified and become customers. If they fail, they will not be customers.
So to end my ramble, the only kind of certification that I would feel to be at all honest would be conducted by an organization completely separate from selling dive equipment, and that had no competition that might draw away customers by having a higher pass rate.
Some people are simply not fit enough to be in the ocean, or are just not comfortable enough in the environment to be safe from panic. For their own good, they should be stopped. But they won't be stopped as long as there is a financial conflict of interest that favors them passing.
End of rant. Next time I'll tell you what I really think of certification.