Idea: your iPhone knows your passwords, so when you make a small typo, it corrects it for you.
There are obviously major security concerns here. But I believe they can be acceptably mitigated by the phone itself. Someone would have to physically use the iPhone to get password correction, and correctly could only happen on the first or second password attempt. Also, correction could be limited to the kinds of typos a person would make.
Passwords are broken by machines, not people. I believe password correction can help people, without substantially helping machines, and compromising security.
It’s hard to type precisely on an iPhone’s virtual keyboard. That prevents people from using secure passwords, and that hurts security. Because password correction helps people actually use strong passwords, it should be to be a net security benefit.