I think this is the first time I've seen anyone else point out that it is frequently deployed as a survival skill by students who are unable meet demands placed on them by other means. That is all the more true in today's high-stakes testing, where anyone unable to perform to demand can have their life destroyed for failure to be pleasing.
Not phrased the same way I usually put it, but obliquely touched upon in several points, is the fact that there are only so many ways to convey certain information and when you have lots of people writing on the same topic, all of them get used up. If you're writing about, say, dreams then your personal input may add a lot of originality. But if you're writing about orange farming in Florida, you have to convey all the relevant facts, and your writing will sound a great deal like everyone else's writing about that topic in order to be accurate. I mean really, look up ten articles on any specific subject such as would be used for a paper. They are going to sound a lot alike, especially once you add assignment parameters like "must be written in academic language" and "2-5 pages" and "with attention to" etc.
As a scholar, I prefer to see sources cited. As a teacher, I know that not everyone has the same level of skill, and that most students have far less fluency with the technical parameters of plagiarism than experts do; they can typically grasp "cite your sources" and you'll get a list of those, but beyond that their awareness falls off sharply. And as a sociologist I know that humans do whatever they must to survive, so if you set them tasks, anyone who can't manage those the expected way will try to find some other method of meeting demands.
If you want to reduce plagiarism, you have to look at why it happens. Leading reasons include lack of experience, response to high pressure, and cultural differences. Those can be improved by more personal education, lower pressure, and cultural awareness. But that requires adults to expend more time, energy, and money showing students how to do this stuff, and more respect for other people's needs and perspectives. That's pretty unpopular. Condemning students as bad is much easier, much cheaper, and strokes the power complex.
The result of that is a great many young people deciding that older people are just irrational, hence the growing indifference to copyright as a whole. Really. More and more people don't even bother to sign their own work, because they don't consider point of origin to be relevant information to preserve, or they actively put it out with "do whatever you want with it" because their paradigm is just that different. It isn't even new. That was the norm for thousands of years until some folks started pushing to put your name on everything. Now a growing number of folks are going, "Yeah we tried that, and it is sucks."
*chuckle* Have fun trying to push the sea back with a broom. When young people consistently differ from old people on an opinion, the old guard is unlikely to win that argument in the long run.