Problems, reliability, and safety are related but different.
Sometimes I wonder what "reliable" means nowadays. Case in point, CR always gives Honda a reliable rating, yet just recently it has been revealed that 5,000,000 Hondas in the U.S. have the defective air bags, which can potentially kill.
Is it better to have a car with a reputation as being reliable, but later found to have a major defect? Naturally, if you never get into an accident then this will not be an issue with you.
The same as it has for decades, "reliable" means "performing as specified." More accurately, reliability is "the ability of a system or component to perform its required functions under stated conditions for a specified period of time." Someone so kindly wrote that in
Wikipedia, saving me from digging through old books buried in my storage room to refresh my memory. (Glenn, was that you?)
What CR measures is the number of problems reported (per vehicle per year by category). They're related but different. Safety and Reliability are also related but different. (Probably only reliability engineers care, though.)
"CR always gives Honda a reliable rating" because it has not yet measured the effect of the flawed airbags. Its data comes from surveys returned by CR's subscribers. Of all the people who own Hondas (and other brands) that have the
potentially defective air bags, only the few who had experienced actual failures (and not died as a result) would have known about them when they filled out their surveys for however many years since they've been put in the cars. That's apparently not a high percentage. As you point out, it's a dangerous problem, but not (yet) highly visible.
The airbag problem won't show up in CR's data until owners who have had them replaced (or fail in a crash) report that in their surveys. Since CR only goes back 10 years, any of the affected cars older than that won't get counted even then. If the carmakers get enough of the defective ones replaced before they cause injuries or deaths, that picture won't change much. Meanwhile, many more Focus owners who had problems with their transmissions and entertainment systems
did report that in their surveys, making them more visible than the problem with airbags.
Oversimplifying a bit, that means that a reliable car can be unsafe, and a safe car can be unreliable. Those two characteristics are measured separately. It's a fair argument that an unreliable transmission has the potential to be be a serious safety problem, but so far I'm not aware of any reports of injuries or deaths from DCT failures. Amazingly and thankfully, so far I've only seen reports of close calls and maybe some peed pants.
Each buyer decides for themselves how to rank them. My preference would be to visit a mechanic rather than a hospital or a morgue. As it was with exploding Pinto gas tanks, people who bought all those cars with flawed airbags didn't know it at the time, so they didn't get to choose. Now we do.