This actually happened to some restaurants who found their service on DoorDash. The restaurant owners were able to make a fine profit out of DoorDash’s arbitrage scheme.

Indeed! Discussed at the time: https://news.ycombinator.com/item?id=23216852

It's worth pointing out that it only worked because doordash scraped their menu incorrectly (using AI maybe?) and used the price of a plain pizza for specialty pizzas. Also it was a trial period where they waved all their usual fees.

Don’t worry. If Amazon decided to undercut by selling at a loss, they would absolutely put it in their ToS that retailers cannot exploit this loophole and they would sue to enforce their ToS.

Retailers could put into their TOS that they are exempt from those clauses when buying things bought from them.

I like this. “By purchasing from us you agree that you cannot enforce your ridiculous terms of service and if you try, you also owe us a pony.”

These manufacturers never signed any ToS, and the most Amazon could do to retaliate would be to de-list the product that they never asked to be listed in the first place.

When the manufacturer buys their own product via Amazon’s service they would become subject to their TOS as a buyer.

I guess they'll just have to use some service to buy for them instead. ;)

It looks like a good idea, this works better for refrigerators than pizza.