This question is an attempt at implementing my suggestion that the second paragraph of that question could be turned into an important question. The discussion starting in comments there would be more interesting under the form of developed answers, in my opinion.
I think most higher educators in maths have felt the despair of seeing so many students
- not being able to check a definition on the most basic examples,
- being clueless on how to solve an exercise that turns out to contain terms they do not understand but that they did not thought of looking up,
- being unable to apply correctly a theorem except by copy-pasting the exact sentence that was used in a previous exercise (and which of course is ill-suited to the case at hand), etc.
If we assume that these problems are entirely theirs to deal with, then we only have to bear it and leave it be. More constructively, let us assume that it is part of our job to help them solve this issues (I do believe it is part of our jobs, and probably the main part at that).
What can we do about it?
A good answer should start with a diagnosis as to where this issues are coming from, and suggest a course of action or at least hints we can use with students. Suggestions that can be carried on individually are especially welcome, but suggestion that involve changes in curriculum or collective action from a whole pedagogical team can be interesting too (they just probably won't happen).