I done me best, but...

Exactly, Biglouis. As a former teacher of foreign languages, I can say that pupils from other countries need to hear correct English. They can get used to local accents and dialect words if they hear them enough, but they do expect grammar to be correct.
Local accents, dialects, pronunciation can be delightful. But if a speaker cannot be understood, they need to do something about it.
Schools have a responsibility to prepare pupils for the world beyond the local school and that includes knowing correct grammar. Many people are bilingual, in that they speak differently at home and at work, and they know which register of language to use in context or home, work etc.
Of course in personal relationships, if you cannot accept someone as they are, maybe a relationship is not going to be viable.

Different dialects use different words for the same thing.
From where I originate,a female sheep ,is man EWE. In the Yorkshire Dales, it is a YOW.
In southern France, a particular alcoholic drink is pronounced as "Burr". In Calais, the same liquid is called what sounds to my Anglicised ears, as "Beer". Which it is not!
When I was child living in and around Wolverhampton, I could distinguish a dweller in Birmingham from a local resident, or someone from Dudley by their accent. And yet they were all saying the same words!
And as for the useage of those dwelling in other lands that speak English! My director (An American) rebuked his secretary for using a "rubber" instead of an "eraser"
As used to be said in Nautical (Or should that be Marine?) circles, "Different ships, different splices"!

AFAIK a ‘rubber’ means a condom across the pond, Puzzled, so perhaps not so surprising!

I once read a novel that was supposed to have been ‘translated’ from American into U.K. English.

One thing the editor evidently missed, was, ‘He patted her fanny as he went past.’ ?