It's like the difference between an old-style Taxi and an Uber, with the latter you just get up and go when you're done. The whole dance of flagging down the server to request the bill, get the bill, oops the server disappeared before you could pull out your card, wait for 10 minutes while they are off exploring Narnia in the kitchen cupboards. Finally they come to take the card and disappear again, what should have taken 30 seconds is now at 15 min+, hope you're not missing your show... ah, finally they're back! Now try to figure out the tip line, with the air of one who is trying to convert Fahrenheit to centigrade in your head while your house is burning down.
Waitstaff-less high-end restaurants expand the audience and frequency of visits of people who can now enjoy these better-than-Chipotle dining experiences. Much like Uber, which doesn't only cannibalize existing providers but actually creates a whole new category of short rides that you would never have previously considered using a Taxi for.