There's no reason to couple the order-taking and the order-fulfilment. At fast-food Mexican restaurants which take the order at the counter, give you a ticket,

There's no reason to couple the order-taking and the order-fulfilment. At fast-food Mexican restaurants which take the order at the counter, give you a ticket, and hand off your finished product sometime later (I'm thinking of District Taco in DC or Pancho Villa in the bay area) throughput is noticeably higher, particularly because they can make more orders at the same time. The one downside is limited backpressure on the order line, so you can end up with more people filing in than there are seats (or sometimes even space to wait for your order). Not as much of an issue for takeout-focused joints.