In Korea, there is a button on every table you can press to get the attention of waitstaff. No more inefficient hoping to catch eye contact when they walk by.
A lot of places now make you walk up to a register and pay as you leave. No more having the waitstaff make 2-3 trips to your table just so you can sign.
Having iPads or something for ordering is another step, but may take longer to recoup those initial investments.
Focus only on a few speciality dishes, rather than offering 200 items.
Edit: there’s also the automat, which was in fashion in the early 1900s in America, I believe. There was the Eatsa chain but it folded, apparently due to “expanding too fast.”