It seems to be statistically correlated, at least from my experience. We used to have a really cheap plan, now grandfathered in with just a handful of users, and those are - to this day - the most vocal group of complainers.

I believe that for some reason, a low price creates more entitlement than a higher price. I have yet to comprehend the psychology behind this, but customers paying up to three times as much complain far less often.