Thanks for adding the clarity. I can understand your point, but you also get that its unfair to paint all companies with that sort of brush.
Because frame-lock slip seems to be a relatively common thing across a range of prices and makers, its important to ensure that expectations are reasonable. I doubt a company is going to get in an RMA knife, clamp the blade in a vice and whack the handle with a shot-filled mallet. I would suspect that they would check for tolerance, maybe degrease the locking surfaces, and maybe do a calibrated pressure test of the lock. This is only a guess, I suspect that if the QC process on that aspect was well known, I'd have heard about it. But maybe they don't, maybe there is some other checking that they do. Lock testing is potentially destructive, so every lock on every knife cannot be pushed to failure, that is just not a possibility. Its also possible that a different QC metric is used in production before-hand as a go-no go, and 99.9% that makes lock testing redundant, but 0.1% of the time the knife would still fail. These are things we just don't know.
There are so many factors that come into play when testing if a lock slips or not, that its hard to take someone's word on it, without them having a good descriptor of the conditions in which it slips. Details get inadvertently left out, and in many cases, if guys find later that it was user error, they are often not inclined to admit that. Understandably so. This is why I think its important to communicate directly with the maker rather than passing the knife off to someone else who then has to deal with it. Maybe your retailer is that better person to deal with it, but I doubt it.