The keyword is "used to". They no longer have it, so they can't fall back to it. Of course they could, and would, go back to shouting numbers, but there's a re

The keyword is "used to". They no longer have it, so they can't fall back to it. Of course they could, and would, go back to shouting numbers, but there's a reason they introduced a pager system. It'd likely slow them down, and with the razor thin margins many restaurants operate at, even a small impact on their revenue could be problematic.