This is not standard or correct in American English either, though interestingly, German uses the same form for both situations ("ich wünsche, du hättest es getan" vs "du hättest es getan, wenn..."), so if that construction is more common in American English it's possible that it's due in part to the influence of German speakers.
That's interesting. While perhaps not "standard", I'd definitely say it is very common among educated US speakers. Not to blame Bruce Springsteen -- who for all I know might have been trying to depict via grammatical error a certain sort of person in his song -- but for me it always brings to mind the song Bobby Jean. But now I see that apparently that is "wished" not "wish" so it's extra confusing :)
Me and you, we've known each other
Yeah, ever since we were sixteen
I wished I would have known
I wished I could have called you
Just to say "Goodbye, Bobby Jean"
