The thing is I think it’s feasible to do this in a non gross way…it’s essentially a search engine that just looks for promo codes, matches them against brands, and then tries them in rapid succession on the checkout screen. I think they would probably need humans to resolve the many 1-off issues (could work in a crowdsource manner like adblock filters) and a central registry to keep track of which ones fail, but it’s not a hugely complex problem.