Right now I pay for several online services, a gym membership, insurance, a student loan, a mortgage, and an auto loan. Every one of these companies has authorization to pull money from my account each month. They all pay their payment processor a significant sum of money in exchange for the processor running the payments and shouldering the risk of the bank not honoring them.

With an API, I could stop relying on this "pull" model and start using a "push" model instead. Companies get my money only when I explicitly send it to them. I could schedule a payment to go out every month for services I want instead of allowing arbitrary vendors to charge my card (banks do have a partial stab at this in the form of bill-pay, but it tends to be pretty bad).

Presumably since the risk of fraud is lower since I authorized the payment with my RSA key, merchants could pay lower fees to their payment processors.

Now, I'm a little atypical, because I know how to program so I could use the API without help. But I know many people who would certainly take advantages of services built on top of an API like this.

Think of all the people in your life who have accidentally continued paying for something they no longer wanted due to the vendor "mistakenly" continuing to charge their card. Or scummy negative-option marketing companies which loudly tout a free product or service and then continue to charge your card thanks to some tiny section in their terms of service.

The possibilities get better too. You could have budgeting apps that don't let you spend more than $X per month for video games, but still allow you to buy groceries. You could give your children an authorized card with a per-month maximum but still allow them to pay for an Uber home if it's after 9 pm.

I really think this sort of thing would be a massive boon to people and society, and it's unfortunate that banks (in America) are fighting so hard to prevent it.