Every firearm background check involves filling out an ATF Form 4473. It’s three pages when printed double-sided, and it must be kept by the FFL (the store selling the firearm) for at least 20 years. Yes, you read that correctly. Your local gun shop is storing an absolutely absurd amount of paper 4473s.
Imagine, if you will, 20 years worth of three-page 4473 Forms and how much storage space that requires. Imagine having to perform a serial number trace and needing to find one specific 4473 in your collection of tens of thousands.