I think it's the personal connection, or the impression there could be a personal connection. You see the person taking your order as a real person, not some kid behind a counter getting minimum wage, and you believe your incentives are aligned - they want to provide the best experience, and you also want that. Also you're right there - you see the grill, the fridges, the cook(s), etc. It is food theatre on a small stage where you play your part in the intimacy.
No, that doesn't always work out, but we feel that it could, even just once, in a way we wouldn't expect to find at Taco Bell.