They decide what the price is. If that price is so high that they can give away an extra product while still turning a profit (which they are, or they wouldn't offer the deal to begin with), then the discounted price is the only price even close to fair. The regular price is them overcharging you. This does not make the discount good.
Now, imagine how much they're overcharging you if they give you a "buy 1, get 13 free" offer. That's what this is.
Why would they lower it? That might hurt short-term profits, which might scare shareholders, which might mean the CEO gets a lower bonus, or even gets replaced. Nah, they'll just maximise profit from their remaining customers by adding in advertising, harvesting data, or even raising the price.
Which is irrelevant to the main point that, no, paying $7 for something worth 50 cents is not good. I save a LOT of money by seeing scummy marketing tricks for the tricks they are.