Now it's pointed out
I see this everytime I go on my clinics formulary and when I tried to explain it to a family member they asked why would they do that to which I replied they would tactically not put products of other suppliers on their formulary to make sure their products shifts to which they replied that if they owned a shop they'd do the same ,but then I explained this is medicine and not commerce and some patients can't get the appropiate medication because of this as alternative options may not be as effective or cost effecient and often patients have pay a hell of a lot of money only to not get the relevant medicine they need or the needed amount.
This causes compromises in choice.