We also do call in orders for take out and you have to go to the counter to pick up the food.

But occasionally I'll hear the dreaded words ”I called in an order." I respond to this with "I'm sorry ma'am but you're going to have to wait in line while I help these other customers." Form here it's a coin flip. They'll either say "I called... Do I really need to wait in line?" Of which I respond with a "yes ma'am" and other times they'll loudly insist I go ahead and help them and I ask them to get in line again.

That... seems like poor logistics on the part of your restaurant? It's certainly not standard practice anywhere I've been to.

Picking up is a really short transaction, and I would cancel my order if you told me I needed to still wait in line behind everyone else placing an order once I arrived at the restaurant.