There are plenty of incomprehensible Americans and Australians etc, precepts you either don't interact with them (poor people?) or you are American / Australian, and don't realise that as a Brit I can have difficult understanding a strong Boston accent.

(I think. One of the characters in "Spotlight" was the most recent time I understood almost nothing.)

Who is "us"? I'm not English, but lived there for more than 16 years. I think I understand most British regional English accents, including Welsh, Scottish and Northern Irish quite well.

> Anyone from any part of the English-speaking world can understand anyone else from any other part,

Try watching an English person ask an American (in the US) for water or where the herbs are.

Yes my point was precisely that many people from England are incomprehensible.