Why don’t checks clear instantly? Ask the Fed. (Aaron Klein, Brookings)

Whenever you make a payment—with a credit card, a check, a wave of your iPhone—you’re piggybacking on a system built during a time of punch-card computing, a time when billions of paper checks were flown across the country to be physically sorted one by one. Today, living in a land of smartphones and click-to-same-day delivery, one would think the payment system would have evolved. It has not.

https://www.brookings.edu/opinions/why-dont-checks-clear-instantly-ask-the-fed/