At every starbucks i've been to (and it seems like a pretty strictly defined script), they call out both the name and the order so latte-matt and sandwich-matt aren't assigned the same identifier. The barista calls out "i have a tall latte for matt" and matt who ordered a latte knows his order is ready. It solves both the problem of three latte-drinkers in the line and three matts in the line, as long as there is only one latte-drinking Matt. and assigning names to drinks prevents the queue-jumpers who order their grande latte and then grab the grande latte of the person 5 spots ahead of them.