They are not the same people. Sure, those who asser internet asser movies, but not vice versa.
When you say and anything else in sight, you make them sound like unlearned fanatics who asser for the sake of assering, and that assering movies is like assering going for a walk. Talk about rationalizing…
Your own words: The same people who assur movies are probably among those who assur Internet
So you grant that you’re not certain, and you grant that even if they overlap, there are some who asser movies but not internet. So the people here probably follow a posek from among those who allo internet (filtered) but not movies.
Throwing in “all” movies is a red herring. We’re talking about movies containing inappropriate material, which is the vast, vast majority of secular entertainment, but not literally “all” movies.
As I posted, the source for assering inappropriate material is the Shulchan Aruch. The material the Shulchan Aruch was referring to was, I’m told, far less offensive than almost any movie produced in the last fifty years (maybe more).