So what you are saying is that if you had known the cost was going to be $1,500 at the outset, you would have kept shopping, decided to wait for a regular appointment or left your foot broken.
At that point an injured/sick person is at the mercy of the establishment.
I will tell you this, however, a month after I broke the foot and the cast was removed, I sprained my good foot to where it put me back on crutches. This was on a Friday, and I waited until Monday when I could go to the doctor instead of going back to the emergency room.
Your explanation of the costs being due to personnel, plant, equipment, insurance, markup, etc. are all well and good and that's what justifies the true costs.
There are two additional factors: revenue and torts that also significantly affect the 'cost'. Torts increase the insurance costs tremendously, and the revenues are severely diminished by illegals, indigents, and other groups (Medicaid, etc.) not paying for the services, the costs of which bounce back to another category in the mix above I did not count - UNPAID bills.