Many descriptivists would argue that the formulations are equally correct because both “occur naturally” in the language. Should a nature speaker learn to say "Dave and me” in their natural surroundings, then this “cannot be wrong”; native speakers cannot make mistakes in their native languages. Similarly, should another native speaker use this formulation, but require correction to say "Dave & I”, then this unnatural speech, the proof being that outside intervention was needed to generate it. Thus, "Dave & I” would only be “correct” in cases where the native speaker have learned this formulation naturally; that is, without the need for correction. Uh, er, that is my understanding of their customary position on such matters.badger wrote: … when I was a youngish child one of the first grammar rules that was drummed into me was that saying "Dave and me went to the park" was wrong & that "Dave & I went to the park" was correct…
Coming back to the central theme of this thread, assigning a nature speaker an inferior status in the social hierarchy based on such minor distinctions of language would be tantamount to elitism. Using language, coded or otherwise, or other social signalling to convey this inferior status to the speaker and to the surrounding community would be paternalism and unjustified discrimination. However, as well all know, the real world frequently operates well outside the bounds of justice and fairness; we’re all human, after all.