Because Japan's demographics made it imperative and conversely our importation of cheap labor subsidized or delayed the need to introduce automation to offset costs.

They're starting to appear. McDonalds has now introduced it in multiple European countries, plus isolated restaurants here and there (e.g. Burgerlich in Hamburg, which has touchscreens embedded in the tables: https://goo.gl/oJAh9v)

Almost every McDonald's I've been to in Europe and Canada has a set of Kiosks where you can order what you want (in English) and pay. You then take a number from the kiosk and sit down and somebody brings your food out to you or screens display your pickup number when it's time. Most ones in the U.S. have stubbornly held on to the less efficient queue at the counter and talk to a bored human system.

You can order McDs on a touchscreen at some locations in Cambridge (Massachusetts not England), it's already made it to America.

There's a burger chain here in the Bay Area called The Melt which has iPad-based kiosks where you can order your food, pay for it with a credit card, and pick up a buzzer (to let you know when it's ready) without having to talk to anyone. It's glorious. I wish all restaurants offered stuff like that.

Coin-operated vending machines for food was actually somewhat popular in the US in the early 1900ds before fast-food. Check out https://en.wikipedia.org/wiki/Automat

Had the same thought when I was in Tokyo and seeing it more frequently in Scotland where there are more self-serve kiosks at McDonalds than there are regular tills.