Thinks americans don't know how people sound
http://www.telegraph.co.uk/news/2016/07/26/dominic-west-being-sent-to-eton-was-like-losing-my-parents/
Dominic says "Americans are very forgiving on accents because they don't really know how other people sound."
That's not it. We are forgiving on accents partly because we don't identify or judge people by their accents as much as others in the world seem to do. We hear so many accents every day and all our lives its just not a "thing" like it is in the UK.
Our parents or grandparents often have accents different from ours. Our relatives and people at school from various parts of the US speak differently than we do, sometimes we speak differently ourselves when we move to different locations. It is so common to hear accent variations here. And in most instances it would be rude to speak of soneone's accent.