I guess I hadn’t thought of this part so much, because if you are someone who does have sensitive information, you probably wouldn’t be signing up to a very new digital bank.
Let’s not forget Monzo is in the early stages of a current account, and the joint account is still in a beta stage.
So whilst your points are valid for the long term perhaps, and it’s always good to raise them, I think we are years away from it being a necessity.
Although Monzo have already said the way they open joint accounts will change.
There seem to be a few issues popping up which seem to try and get Monzo to cater for absolutely every situation and circumstance - It’s just not viable right now, and the reality is, if it doesn’t work for you at the moment, it’s probably best to avoid.
That’s not to say it won’t change of course, but there is SO much to develop already, that inevitably, you will need to cater for the wider audience before drilling down into the niche examples.