English is spoken by over a billion people. Many of those people, even ones who are native speakers, have accents that are nearly incomprehensible to American English speakers. There are even debates about whether some dialects of English are actually separate languages at this point.
See: https://en.wikipedia.org/wiki/List_of_dialects_of_the_Englis...
See also: http://dialectsarchive.com/
It's completely unrealistic in today's global world to expect everyone to speak with the same accent.
Talk.