Changing all the words to say the exact same thing as a previous piece of writing is also plagiarism.
If this is the case, we are all criminals.
[We are talking about students], not professional writers or "experts" in any field.
Students have the same tendencies as all "experts" to prefer one topic area over another, especially if they have personal experience with it through their work or through previous research. This makes them experts, at least in the strict legal sense: "One who is knowledgeable in specialized field that knowledge being obtained from either education or personal experience" (
Black's Law Dictionary, 1991, St. Paul, MN: West Pub. Co., p. 572). This is what makes people "expert" in something, after all, so it is logical that many students would focus on one area of specialized interest, especially one that is relevant to their career field (i.e., smartphone apps and marketing). Anyway, you're right, I should have been clearer, but I think you're creating a double standard for us (professional writers) and them (students and clients) that is, in my view, at least, sanctimonious.