[undecisive]

I find the logic here really interesting. When you participate in a buy-one-get-one-free offer, you "leave with things you didn't pay for". So imagine these scenarios:

You go to a greengrocers. The lady at the checkout sees you basket of 27 grapefruit and can't be bothered to do the maths, says "let's call it 5 [relevant currency]". You know you have something in the region of 7 relevant currency, but she insists she won't take a button more.

You go to the supermarket. The tills are misconfigured, a 10[currency] box of chocolates is coming up as 0.1[currency] [1]. You're buying 5 of them. The cashier has no facility to charge you more - whatever the system says is a divine edict as far as the company is concerned.

You go to the supermarket. You're walking by the main doors with your trolley when a fire alarm goes off; smoke is billowing from the back of the store, sprinklers are activated. In the blind panic, you - and your trolley - are pushed outside. After half an hour, they announce that the store will not be reopening. You tell security that you have not paid for your shopping, they gruffly request that you take it home and make use of it rather than litter the car park with rapidly defrosting frozen items, as nobody is allowed back in the building.

In most of these cases, you could probably pay the correct amount by queueing at another till, at another time, date, at your own time and cost. For the benefit of someone who doesn't care enough about the profit margin to worry.

These are much closer than your employer-theft analogy - I don't think that the parent poster's moral standpoint is at all far away from any of the above. In fact, the only difference is that because it's a technical "glitch" with no humans involved, you clearly feel you're supposed to go the extra mile to rectify the seller's mistakes, caused by the seller failing to invest sufficiently in the system.

I certainly wouldn't judge someone making any of these calls, regardless whether I personally would go that extra thankless mile.

[1] https://www.telegraph.co.uk/finance/personalfinance/money-sa...

[mindslight]

I think the closest, albeit boring, analogy to the situation is you go through the traditional staffed register at a busy time. The tally comes out a little lower than you were expecting. Since it's not higher, you pay and get out of the way. In the parking lot, you look over your receipt and see that one item out of many didn't get scanned. Now you have the choice of either just accepting the benefit from the mistake, or spending your life waiting in line again simply to redo their job better than they did it themselves. IMO it's foolish to correct their mistake by harming yourself instead.

I've also corrected cashiers on the spot, especially for more significant errors. I once had a cashier ring up a manual 20% off coupon as 80% off ($20 vs $80 final price). Going through with that transaction could reasonably be called dishonest, despite it being perfectly legal.