Many couples would find it just as annoying as having separate refrigerators and simply transferring food between the two before withdrawing and eating it.
Account-to-account internal transfers is relatively new and they did not have that feature when I was approved from the beta.
But, account to account transfers does not solve the problem at all. I don't want to have to transfer money from my account to my wife's account manually. It's so much easier when she can just access a shared account and move money as needed.
Why not have one account for each of you? Simple has instant account-to-account internal transfers.