I attended high school in the US in the early 00’s and cell phones were absolutely banned from classrooms. You could keep them in your locker and use them between classes, but that was it.
I attended college in the late 00’s, and I don’t think I took a single digital exam. Quizzes, sure, but for final exams even CS was pencil and paper (or a final project, which admittedly will have issues in the post-LLM era).