I haven't seen this anywhere so I figured it's worth asking. I'd really like to have a read only token that could be issued by my bank so I can have a little web client pull the balance data and update a budget for me. Yes I know there's mint budgeting and all that. I'm skeptical of handing the keys over to others and I'd like to DIY this. Is there some regulatory reason this doesn't exist? Are there any banks that have API access that clients can't use? Every time I switch banks to something that has cash envelope accounting they take it away or merge with another bank and I have to start the whole process over again. I'm beginning to think it would be easier to just do it myself if I had API access. | 
As the SVB episode has most recently demonstrated, in fractional reserve banking, an individual with a deposit account is not a customer of that bank. They are a creditor. More importantly, as with users of free services, they are the raw materials from which banks create the actual products- loans- for their actual customers- businesses- usually- to whom they lend.
Consumer banking, ironically, is not a business any bank actually wants to be in. It is a loss leader, complicated, and inconvenient.
Individual level API access to deposit money is on no bank's top 100 (or 1000, or 10000) to do list.