Banks are themselves full of absurd practices but in this one tiny area I’d give them a pass.

A couple of years ago I used DocuSign on a contract, and the PDF “copy” I was emailed as a receipt had different terms than the one I actually signed.

Luckily I did not object to the discrepancy, but I would have wondered what would have actually happened if I did.

Regardless, I am sure there has been a version of a some document signing software somewhere that had a bug with immutability. Now paper documents aren't immutable either, but you couldn't accidentally change one with a bad where clause in a SQL statement, and casual attempts will leave evidence of the change.

BTW this is why numbers in contracts are often written “1 (one)”: because in the age of pens it was easy to change “1” to “10” or “4” or “one” to “none”

Also why checks do this — checks are actually simply contracts, which were standardized in the US a bit in the 1920s (you’d get a check form, fill in your name and the bank name, then the amounts, etc; current check design With preprinted bank info dates back I believe to the late 1960s.