> But the restaurant is worried about you stealing their food and dashing off without paying.

Except that they serve you before collecting payment regardless of which payment method you use.

And even if they didn't, having the customer pay at the same time they receive the food isn't a trust problem for the restaurant or the customer, because the customer gets the food before the restaurant gets the money but the restaurant gets the money before the customer eats the food. And if someone comes into your kitchen to steal food without paying, that isn't really a payment system issue to begin with.