The money is a thing, not that I can't afford it but suddenly being told you're going to pay 6 euro extra without getting really much is a bit jarring and not nice. At the very least it would've been smart to stop taking new Joint accounts but phase out the old ones over a long time, that would have saved a lot of yelling on social media ;-)
Anyhow, what I'd suggest is to make the 'joint' account more than a pack of two 'light' accounts, but try and indeed focus it on 'joint' factors:
- must live in one house
- by default the cards take from one bank account and all accounts are jointly visible and add up to one amount, not separate
with this last one I mean - look, my and my wife, we have a joint account. So I expect, when I look at the amount of money, to see all the money we both own. We don't have anything separate, and don't want that. But if she creates an account and puts money on it, it suddenly isn't visible. That is very annoying for us, to be honest. I'm of course fine if she has an account she handles how she wants, it isn't about that, it is just about visibility - I want to see how much "WE" collectively have, so I can decide to pay back extra on our mortgage for example. But if some accounts are not visible, I lack that transparency.
So integrate Joint deeper. Make it a real, shared account.
Honestly, I might have gone for ONE premium account and give her 2 of my 4 cards if that was doable - it is essentially what imho a Joint accounts should be.
Does that make sense?
And yes, as added benefit, this will mean it isn't a discounted way to get two premium accounts - two independent people would not want a Joint account. Which is fine ;-)