Check ID address, ban people caught reselling, etc.

Get creative you're now a destination restaurant and can charge $50+ a burger. Or go out of business I guess.

Doesn’t matter. It’s still rate limited.

I wonder if you could switch the 'locals only' card for just requiring proof of address on a driving license or utility bill. Might still be a problem with locals offering 'burger tours' - you pay me $10, I buy the burgers for $5 because they'd charge you $20, everyone is happy (except the restaurant).

To who?

Someone that is only going to go there once or twice? Then it won't cause a problem.

Someone that isn't a local, but goes to the place over and over anyway? Consider them an honorary local.

To what end?

The whole idea is that non-locals are probably going to buy 1 burger per year or perhaps lifetime.

These kind of people don't fiddle with ebay and paying a random guy just to get 25% off of a burger that they will use once.

But then the local doesn't get the discount burger, and the out of towner gets to use it once.

Presumably it would also expire, so it would be that locals loss rather than the restaurants.