From what I can tell, if no rule is enforced, about 2-5% of people think it's totally normal to scroll tiktok or instagram at full volume in public.

So on a crowded bus you've normally got 1 or 2. Behavior is actually much better on airplanes, usually (maybe 1-2 in ~150 passenger plane), and I have never seen someone who did not silence their phone after being asked politely by the attendant.