Kelli,
Unfortunately, this is SOP for most garages. You could call and tell them you have a flat tire. Even though, most people KNOW what a flat tire looks like, and the techs KNOW that most people know what a flat tire looks like, they won't order the tire until they see for themselves that the tire is actually flat. That's an over-simplified explanation, but, that's the way it works. They only have inventory on hand for "normal, recurring" problems, on the cars they see the most of. Otherwise, it's an order. Subaru only allows orders to come in on a certain day (tuesdays, I think) and it can take anywhere from two to five days for the parts to arrive (unless, of course, someone leaves it on the truck, the truck goes out of service and is parked in the back of a lot for a week awaiting maintenance, like one time when I ordered a wheel bearing for my Suzuki . . . oh, sorry, I got off subject). Independent garages usually order through dealers (unless it's a simple A/M part like Beck Arnly or similar), which also ads time.
I know how you feel. Practically EVERY time I've taken a car to a dealer, promises are broken, and it winds up costing me more than the original estimate.
I need to be quiet now, before my blood pressure begins to rise, thinking about the previous experiences.