It has been a few years, but my impression of the coin-operated stand-up ramen shops I frequented in Tokyo was that the cook and cook's assistant were the only people working there, and they often had no time to spare dealing with money. If labor costs must be reduced, it seems better to cut the cashier than the cook.

Personally I think its great most of the time. Human interaction should still be an option, especially when it comes to specialty orders. I always felt something like this could work well at places that have a lunch rush in America. A string of machines that don't accept substitutions and only credit cards, along with a line for people who want a human to take their order.

This was called automat in the USA, popular in the 1970s.