That can very easily be a design flaw of the engine or the lifter. Sure, some go 300K, but others fail under 50K. It doesn't need to fail 100% of the time to be considered a design flaw. Look at many recalls for bad bolts, tires or harnesses, etc. They recalled them all and replaced them all. Not because all of them failed but enough did, and they figured it would be better to replace them all than take a chance. And that's just it with the lifters, has the number of failures exceeded the point that Ram does something? Now if these failures caused accidents and somebody was injured or killed? You bet there would be a fix in place.
The specific failure mechanism of the Hemi lifter issue would need to be identified, which, as far as I know, no one has done yet. Lots of speculation, but nothing concrete. And honestly, I would lose all faith in Ram if it were in fact, just "bad" lifters from supply. That's BS. If you are getting that many bad parts, you get a new supplier because that's unacceptable.