On a kind-of-related matter: a shoe shop in my city doesn't provide receipts - rather, it provides the credit card receipt (of negligible value!) and then, if a pair of shoes is over a particular value, it'll write the model, purchase amount and date on a loyalty card - this provides a discount after purchasing so many pairs.

I've always found this a bit weird, especially given there's no proof of purchase provided if a pair costs under the threshold (which can often be the case with say kids' shoes), or if someone doesn't elect to hold a loyalty card.

And now it's come back to bite me as I've taken a pair of faulty shoes in to get sorted - they've asked for proof of purchase. I've not got that specific loyalty card, as I've since redeemed my discount; they may or may not have returned the card to me, but I certainly can't recall being given it back. So now I'm trying to dig through my credit card statements for some evidence of the transaction...

Anyway, how appropriate (or legal) is it for a company to not provide a formal receipt for such purchases? This is the largest shoe shop in town, so not some fly-by-nighter.

Worst-case scenario I can think of is someone paying cash for a pair of shoes under the limit to qualify on the loyalty card - for that purchase they'd have nil evidence of having made the purchase!

Always have written (or electronically written) proof of purchase. It makes things easier. It's not about what's legal or not.

It's like driving. There's a car at the intersection, slow down. If there's a crash I may be in the right, but not crashing makes things easier.