There is a new series on TV here in the States called Outlander (based on the books by Diana Gabaldon) set in 18th Century Scotland. It's breaking new ground as far as language is concerned; much of it is in Gaelic, with no subtitles, and there are also a lot of Scots words thrown about with no subtitles or translation. Clearly, the US producers are expecting their audience to understand much from context. (It's a US production but filmed in Scotland primarily with actors from the UK and Ireland.)
We're watching Outlander. I really like it. I think Jamie is super dreamy.
I think TV companies are just weird about accent and speech, I'd be subtitled on TV outside of Scotland, but I've never met anyone who couldn't actually understand my accent yet. (You know if I use real words and make an effort not to say things like wurruld instead of world, lol)
I've seen American tv shows were they use subtitles for American people. Granted, some of us speak a bit lazily, but I've never had a problem understanding anyone if they were speaking English. I guess maybe other people do, though. There was one time I was speaking to a co-worker about seeing the movie Love Actually, and she said, "is that one of those movies where they speak English?" to which I responded, "Yes. What language to you think we're speaking now?" And she said she doesn't like movies with people with accents. :/ My husband and I watch a lot of Japanese horror movies, so I'm used to subtitles, but they bug me when the person is speaking English.