Let's say that you're waiting in line at your local coffee shop.
Emphasis on "Coffee Shop."
It is not a pharmacy. HIPAA does not apply. The person in front of you is not giving out sensitive information and, in most cases, will not mind if you overhear an order for a nonfat soy double latte, or anything else on the menu.
It's a coffee shop, not a bank. You do not need to stay behind some invisible line and wait until the Next Available waves you over.
Rather than force the line behind you out the door, please, move up. Really, it's OK. And if someone gives you trouble, tell them to talk to me. Especially if I'm waiting, un-caffeinated, in a cold rain.