IIRC prior to being treated you agree to be financially liable for the costs. Prior to even knowing that that will be or even the costs involved. Or even if you know what is involved are you going to understand what a reasonable cost is? EG: Sling is easy but what about a x-ray study? Is that 200$ or $150?
Just like a proper capitalist system! You know, like when you agreed to pay whatever for your iPhone prior to even know it'll work.