Apparently a lot of people disagree with you:
So you load up the trunk with rice and drive over to that nice 'retired' sawbones in the next town. He does the exam and agrees with you that surgery is in order. He requires a half ounce of gold or ten ounces of silver. You tell him about the rice and he laughs as he shows you his storeroom packed to the ceiling with rice, flour, booze, bullets, and oh yes, boots.
He explains that his suppliers for drugs, tools, sutures and the like only take gold or silver. "But, but, but on FreeRepublic I saw many times that that stuff was worthless," you moan. "Sorry guy, but times are tough all over," the surgeon intones.
Now I pray that this never happens to you, but if it does happen to me, I would rather have it and not need it, rather than need it and not have it.