That's a fair observation. My personal experience has a bias because I knew a math and computer science major who was hardworking and seemed bright at academics

That's a fair observation. My personal experience has a bias because I knew a math and computer science major who was hardworking and seemed bright at academics, and he was really into Anki. Knowing him led to my impression that a decent number of math and physics students might have studied with spaced repetition without talking much about it, as he only mentioned it after he saw me studying with the software once. But in hindsight, I agree that it's more likely that math & physics students stick to the learning habits they developed earlier on—often through lots of practice tests and exercises. Anki seems to be more of a natural progression for people in other fields like biology, where students might develop habits of using flashcards with software like Quizlet, where using software with better study schedules like Anki can be a natural progression.