any specific food has a at least one if not many near perfect substitutes, whereas any specific drug likely does not. validity of OP's conclusions aside, this

any specific food has a at least one if not many near perfect substitutes, whereas any specific drug likely does not. validity of OP's conclusions aside, this is not apples to apples from an economic perspective. see also: https://en.wikipedia.org/wiki/Commodity https://en.wikipedia.org/wiki/Commodity https://en.wikipedia.org/wiki/Fungibility https://en.wikipedia.org/wiki/Fungibility https://en.wikipedia.org/wiki/Substitute_good https://en.wikipedia.org/wiki/Substitute_good https://en.wikipedia.org/wiki/Price_elasticity_of_supply https://en.wikipedia.org/wiki/Price_elasticity_of_supply https://en.wikipedia.org/wiki/Price_elasticity_of_demand https://en.wikipedia.org/wiki/Price_elasticity_of_demand etc.