They carry no authority at all. A charter can require one and reject the other if they choose. It may not make business sense but they can do it. Nothing you can do about it. Nothing PADI can do about.
Well, scanning this thread, it seems as though the rest of the world has already moved on. Hopefully your charters in the US will catch up one day.
In the meantime, I still hold that ecards should be the default and the traditional cards available upon request, possibly for a small fee. £30 though, that's just too much.
Ooh, just think, if PADI stopped issuing the traditional cards as default, it may force some of these charters to educate themselves......