[ShroudedNight]

> they don't then turn to their providers and say "since we sold this at a discount, we're going to pay you less for it".

Not necessarily because of sales, but one of my parents' neighbours (he was previously a fairly senior guy at a flour manufacturer) spoke from experience of big supermarket retailers "renegotiating" unit price after the fact (and after delaying payment until duress) under the threat of removing all their products from sale if they don't accept.

[eru]

Aldi has such a good relationship with suppliers, because--despite driving rather hard bargains up front--they do stick to what they agreed to pay and don't pull shenanigans.