A service could pop up that offers to double spend your $5 transaction and refund you a percentage of the amount. If they mine the block you scam a few bucks, if they don’t you paid full price. It would be profitable for the miner and for the burrito buyer at the expense of the burrito seller. If such a service becomes common, that seller is going to start making you pre-order your burrito 20 minutes in advance – at which point people will just switch to cash, credit, or a blockchain without these problems.
you can also walk out of the store with the burrito without paying but that is also stealing. this small transaction issue will be solved technologically but the changes are incremental because of the risks involved.
