> The real problem is that the app companies have very little incentive to stop fraud
The app companies have plenty of incentive to stop customers from defrauding them (e.g. by using stolen credit cards); they simply have no incentive to stop customers from defrauding the restaurants, because that doesn't come out of their pocket.
The delivery platforms have a near-monopoly and are equally scummy, so unless you’re a household name customers will jump through extra hoops to order from (like going direct to your website), you have no choice but to accept this if you want to compete.
Presumably more people are tied to their platform installed (UberEats/Deliver/JustEat) than a restaurant. If "that random pizza place across town that I order from in one click" disappeared off deliveroo, many people would just go to the next restaurant on the list.
It also wouldn't surprise me if these apps/sites delisted them in such a way that if you go looking for them they tell you they're "not accepting orders anymore" and just suggest an alternative.
The app companies have plenty of incentive to stop customers from defrauding them (e.g. by using stolen credit cards); they simply have no incentive to stop customers from defrauding the restaurants, because that doesn't come out of their pocket.