There are two things tangled up here.

(1) Using a language or dialect based on your audience.

This is code switching. Code switching is done to empathize with and/or establish credibility with the target audience, to make things easier to understand for the target audience, or (in the other direction) to fill in places where the speaker has deficits in knowledge of the dialect or language best understood by the target audience.

As I illustrated, everyone learns how to do this at some level. Everyone, with a moment of reflection, can know what it's like; some people may have to do it more than others. The teenager example is not a joke. You have most of the elements you pointed out--different pronunciations ("yaas"), spelling ("smol"), grammar ("fine" vs "fine."), etc. (SMH).

If you need to code switch but you haven't learned how, I reckon you'll sound like a bloody drongo, mate.

Which brings us to

(2) "ESL" among native English speakers who have a different dialect than "American Standard".

Schools tend to do a poor job teaching anyone who doesn't fit the very most common mold unless they fit into some other box that can be dealt with non-individually.

Given this, it's important to recognize that speakers of AAVE (or other dialects of English) may need explicit support to learn the dialect used for instruction.