IMO, a not-insignificant factor here is attention - most people are doing two things (at least) while watching TV these days. They aren't fully tuned in and actively listening to hear what's being said in English speaking shows, even with heavy regional dialects. You can definitely follow these shows, you just have to "be there".

Second observation is actually around Neurodivergent people. I find certain people fixate on understanding exact language and meaning in TV shows/movies, when in reality, much of the content speaking to multicultural audiences know that you won't exactly understand every cultural reference or specific phrase - when the Italian mafia boss shouts quickly with angry eyes and runs the back of his hand under his chin at someone... You don't need to know specifically that he said, "your mother is a prostitute who sleeps with goats". You're meant to take the general context of that moment from tone and body language. ESPECIALLY say, is the person he's yelling at in Italian is American for example, that confusion you feel personally adds to you emphasizing with the fear and confusion of that character who doesn't understand what's being said. Many though can't break that fixation on needing to know EXACTLY though, so I know people that keep the subtitles on.

I think some people should probably just be trained to consume media properly, and they may respond well to that training if it existed somehow. Problem is, all of the networks are owned by huge multinational conglomerates. They don't care at all about the art or the split attention, just that they have captured that diverted attention in both places that you're half focusing on.