I deleted all my Mint stuff years ago just because of the security concerns. If you mention the security concerns on Hackernews, a Mint employee typically replies with a link to the wikipedia page on their patented security model. Still, I'd rather not type all my bank passwords into an Intuit website.

I like your concept of the multiple credit/card style budgeting. That makes a lot of sense. There are even some of those multicards out there with an e-ink display to select different cards. A bank could just issue one of those for a fee where you can select the account (and have a way to transfer money/items around if you select the wrong budget option).

Discover card has a section in your UI that tries to automatically break down your spending by store type (grocery, gas, etc.) but it does require you make all purchases with your Discover card, which a lot of people simply don't take.