I always wonder what it is that prevents people from switching to a more standard version of the language, is it not obvious the message is getting lost? is it some sort of pride in the accent? lack exposure to foreigners?. I've experienced this many times in Spanish, English and German.
Sometimes, there is no standard version of the language. With British English for example you used to have Received Pronunciation (RP) but nowadays it's not that widely used anymore. It's also associated with social class. In some ways it's always been an artificial accent only people from a certain background used consistently.
These days, even BBC TV presenters often use their respective regional accents (Still optimised for clarity and comprehension, though. You won't hear a thick Glaswegian accent from BBC newsreaders).
Arguably, there's "Modern RP" but in many cases that's just a South-East England / general London (i.e. non-Cockney, non-MLE) accent.
Anyway, you probably need to have some linguistic awareness to be able to recognise and make these distinctions for your own speech and change your register accordingly.
And after years of conditioning to sound "right", it's very hard to unlearn all that and sound "wrong", in order to perform that accommodation.