I think it's just unrealistic expectations about what learning is like, how long it takes, and what you do to learn.
In part, perhaps it's from the educational system which curiously enough isn't geared particularly well toward learning. It used to be geared toward the needs of teaching (which is not the same as learning), but lately it's been geared toward passing standardized tests. Someone going through such a system might be excused for thinking that the way you learn something is by cramming facts until you can repeat them once and then forgetting the whole thing because that test isn't coming back.
In part, perhaps it's from the educational system which curiously enough isn't geared particularly well toward learning. It used to be geared toward the needs of teaching (which is not the same as learning), but lately it's been geared toward passing standardized tests. Someone going through such a system might be excused for thinking that the way you learn something is by cramming facts until you can repeat them once and then forgetting the whole thing because that test isn't coming back.