It's the older players that fail to realize that what they're doing is wrong.
...or it's the older players who realize how the game actually works, and how little the "common morality" actually means.
However, OP, nothing can be done about this issue.
Actually, there are quite a few, but they involve replacing the old "need / greed" format with something that doesn't pit players against each other. E.g., independent and private rolls on loot tables; awarding each teammate a random amount of crafting mats or "loot tokens" or what have you; etc.
I understand why game designers like the need / greed system (and hence why it probably won't be replaced), but it's beyond me why players have become so invested in it that they'd rather make "play nice" rules than question its existence.