Ashes to Ashes subtitling?

[yendi]

Could someone please explain why BBC America feels the need to randomly subtitle some (but not all) lines of Ashes to Ashes? They're not lines that are spoken by only certain characters, or when noise is playing, or with thick accents, or whatever.

Also, why do they feel the need to open every commercial break with a preview of what's coming up after the break (a feature that's annoying enough on non-fiction shows like Ace of Cakes and Mythbusters).