Okay, so no one asked me this; I saw it on Twitter, from my friend Brian Beutler, re-tweeting Business Insider's Joe Weisenthal:
"Wondered this for years. RT @TheStalwart: Why aren’t physical receipts always opt-in?"
As it happens, there’s an easy answer to this question: Because except in a few places (such as taxi cabs and hotels), the receipts aren’t mostly for you. They’re for the employer.
Ask yourself: Why does Banana Republic give you a receipt? Are you going to deduct your new sweater? Charge it to your employer? Are you unaware how much you just paid three seconds ago? Are you going to go home and laboriously enter your purchases in a ledger kept for just this purpose? No, no, no and no, in most cases. So why do they give you a receipt? And it's not necessarily for returns.
Instead, it's mostly so employees can’t steal.
The history of the cash register is, by and large, the history of theft prevention. Oh, they were originally created as tallying machines for very high-volume businesses. But it was hard to convince businesses that they needed to spend $150 or $200 on a machine to hold cash, at a time when a good workman might earn a dollar or two a day.
The great innovation of the National Cash Register company was to market registers not so much as adding machines but as devices for preventing theft. Here’s Walter Friedman’s "Birth of a Salesman" on how these machines were made ubiquitous:
Because of the high price of NCR cash registers, sales agents had to convince proprietors that the machine would eventually pay for itself. NCR's early advertisements resembled the contemporary flyers of life-insurance. In both, the aim was to heighten customer fear and uncertainty. In the cash-register trade, the fear centered on stolen revenue. One of Patterson's advertisements, proclaiming "Stop the Leaks," depicted shop owners ruined by clerks who stole from their cash drawers 20 This marketing strategy posed problems for NCR, because clerks and bartenders resented the implication that a mechanical "thief-catcher" was a necessary coworker. Some even organized protective associations to keep the product out.
In instances of intense opposition by clerks to newly installed registers, Patterson sent detectives to supervise the machine's operation. NCR for June 1888 printed a letter from a merchant in Detroit whose store had been watched by an NCR-hired detective. "Your operative's report relative to my man not registering is at hand. I was very much surprised, as it caught a man, above all others, I have relied upon, not only in the bar but in other matters in the house."
That’s why cash registers ring loudly when the cash drawer opens -- so that a clerk with decent mental arithmetic skills can’t pretend to register your sale and then pocket the cash. And that’s why you get a physical receipt -- so that the clerk can’t ring up part of your sale, and then siphon the rest into his own pocket.
They give you a receipt every time, annoying as it is, because they know you’ll glance at the total and notice if it’s very different from what you just paid. And maybe ask the clerk why, in the hearing of their manager.