Every pharmacist and, moreover, every consumer capable of conducting a transaction with said pharmacists is also capable of spending the two minutes* required to evaluate the difference between these two auto injectors.

Evaluating the distinction doesn't require anything close to an advanced degree but it's not legal for anyone who isn't credentialed to vend/dispense/trade/exchange/grant/supply/provide the still-very-effective, much cheaper alternative based solely on the customer's informed demand--doing so would be "illegal".

Yes, if your highly-trained, well-payed, in-demand pharmacist has the time and interest; they can work through the call tree until he reaches your highly-trained, well-payed, in-demand doctor; who would've wrote a more general prescription in the first place if it didn't increase their chances of being sued, and get the prescription changed. The problem is, apparently, that hasn't happened often enough--probably because it doesn't happen for free. Someone ends up paying for it e.g., the doctor and pharmacologist, other patients, the insurer and their other clientele or the tax payer--multiplied times however many epinephrine injectors are sold in a given year.

There are few incentives to economize in the chain of payers because health-care is an unlimited 'right' that should be provided for by someone (everyone) else: https://en.wikipedia.org/wiki/Tragedy_of_the_commons

* Link from above: https://www.youtube.com/watch?v=LRgqwgCh4Fs