Thanks for the overall feedback.
I agree this is a long way from an ideal study. If I had wanted to publish in a journal I would of course have raised the bar significantly... but this is a forum.
Since you made it a point to state that you had engineering expertise, you raised that bar by implying it would withstand engineering scrutiny, but, IMHO, it doesn't. As a licensed registered professional engineer, I found that comment to reflect poorly on the engineering profession.
There are many reasons for camera failures, and shutters are only one of them. I suspect, but have no actual numbers that the average consumer camera has well under 15,000 shutter cycles, I've bought two dozen and none of them had nearly that many when I later checked them, and none failed. Without accurate numbers and information about the camera population, its impossible to put the data into perspective. If, as I expect, 90+ % of the cameras of a given model have under 15000 actuations, then the numbers do not make sense. We don't know.
Reliability does indeed involve infant mortality where failures happen more frequently after a new product is put into service. Usually, electronics is the most affected, but mechanical items suffer from the same issue.
Heat is the big reason driving failures, but cold can be bad as well. The thermal expansion / Contraction can literally tear things apart in short order. Product wearout usually happens after a long period of use. Obviously, vibration and shock can also destroy a item, but heat is a killer. A camera that is left in a hot car can have its life shortened considerably.
Then, there is the sensor. They tend to get more hot pixels over time, so a older one will suffer. There is no information about newer sensor designs, so hopefully, that issue is being reduced.
When buying used, I would have no concern about a camera 6 months old with a few hundred cycles, because the electronics has been burned in, and any mechanical issues should have been found. The one area where there would be no information is exposure to high temperatures as found in a car on a hot summer day.