I don't agree that adding Off/Auto/Language-of-choice setting is complicating matters. Having an "Off" setting that isn't actually off is not good UX. A huge portion of Spanish speakers in the US also speak English, so I wouldn't say this is a niche feature.

44% of Californians speak a language other than English at home, and 1/5 nationwide [1], yet Netflix' product doesn't seem to cater particularly well to those audiences.

https://www.cnsnews.com/news/article/terence-p-jeffrey/censu...