[throwaway9d0291]

I'm aware. The first link I gave says as much.

However while it's accepted in regional spoken US English, it's not accepted in written English, even US English.

As for evolution, language does indeed evolve but only when changes are accepted by a significant number of speakers. No matter how much you wish it, you can't simply start forcing a linguistic change on society without society agreeing. If you start to spell "agree" as "agrii" for example, nearly all English speakers will (rightly) tell you that you're wrong, you can't just respond to them with "language evolves". "On accident" is still rare enough that we have a choice to reject it and that's the choice I'm making.

Also, remember that there are non-Americans on this site (I'm one of them). To us, this is simply incorrect. We don't have exposure to this kind of US English in most of the American media we consume (TV, movies etc.).