How does the cost of a drug change based on who is consuming it? That's like saying the cost of a loaf of bread changes based on who is buying it.

The price you charge for the bread might change, but the cost is the same regardless of who is purchasing it. There's a difference between varying costs of an item based on accounting methods, versus varying costs of an item due to who is buying it. There seems to be huge disconnect here between people working in healthcare, and pretty much everyone else.