It seems to me that the money question confounds two factors. As I recall (possibly incorrectly), studies find that increased pay doesn't correlate with increased work / productivity. That's probably true. If I'm working on a problem that I want to be working on, it would take relatively large swings in pay to motivate me to work more or less hard than I otherwise would.

And yet I'd bet that money does have a significant correlation with retention and satisfaction. Perception of insufficient raises will certainly lead to dissatisfaction. Offer of meaningfully more money at a different job --> who wouldn't want that if the work is otherwise as good?

So in other words, productivity != retention.