I'm just seeing what looks like an attempt to sell me a PDF.

What actually is the source of such costs? The cashier still has to be paid even if the customer is using a card. Presumably there isn't anywhere near that much theft from registers, or people messing up giving change?

Employee theft. Store manager theft. Robberies. Counterfeits. The extra time spent at each cash transaction and re-counting at the end of the day. Going to the bank, or paying an armored car service. Banks charge merchants a percentage of each cash deposit. Buying safes and pointing cameras down at each register.