Ben, glad your son's OK. Looking at it a different way, my home has experienced some damp walls over the summer from all the rain. I had Waterworks scope the downspouts around my house. Flushed some clogged lines and used a camera to inspect for breaks. $450 well spent, I say. I didn't have a $$$$k See-Snake camera. I could've started digging up downspouts to guess where the problem was instead, but felt our home and one of my single largest investments was worth a professional examination.
I'm cheap, and there's a point where you have to acknowledge the costs of people, as well as amortizing equipment and resources per procedure. For $500 you knew your son's foot wouldn't be a problem. I'm just suggesting that what you paid isn't THAT out-of whack. If it was $1500, then your story would be more relevant.
Not Urgent Care's fault (or their staff or equipment) that you didn't gamble your son's health on DIY medical work before going to their facility.
The bigger discussion point that we're evolving to in this thread is PERSONAL RESPONSIBILITY. If you take care of your body, get checkups, you won't be as big of a drain on our medical system. If you eat junk food 24/7 from WalMart, then get diabeetus and other medical complications, you become a drain on the system's resources.
You want socialized medicine? Prepare for everyone else's shit to be something you're financially accountable for as well.