I think because that's improper grammar in English. So, it would make more sense as "This does not concern me," or something along those lines.
Modern English requires "does not" to make a sentence negative. However, you might have heard someone say the equivalent of "That concerns me" (-- pause --) "not". It seems to be entertaining because the first part of the sentence implies one thing, and confuses or astounds the listener, and then the sentence is negated with "not". This type of speech is meant to be "silly" or "fun" rather than serious conversation.
Yea, I answered the same. Weird that its wrong since the first translation that comes up for "betrifft" is "concerns/is concerning"
Yes, I think "does not apply" is a valid translation. Also, "that does not impact me" should be accepted, but it is not at this time (September 2017). In fact, I think "impact" would be a better translation. Duo is still learning all these languages, too.
Should be accepted. We need to help Duo learn more English so he/she can accept more translations.
Probably because that's not proper grammar in English. In English we would say "that does not concern me", meaning it doesn't affect me at all. Saying "that does not regard me" or "that is not regarding me" means that it doesn't involve you, or that you're not at fault.