[Svartalfiar]

If this man can scan tickets for the “see retailer” message on his phone, what prevents shopkeepers from doing the same with each roll of scratch-off tickets?

You have to scratch off part of the scratchy-part to reveal the barcode to scan. So it would, obviously, be a major flag if a shop was selling tickets with those already scratched off.

Next time you buy a lotto ticket, don't do the whole thing, only scratch the game numbers part. When you give it to the cashier, you can see them scratch off the barcode area to scan and verify.

[NautiNurse]

Ah ha! Mystery solved. Thanks.