it simple, they wont pay for expensive ones at all. brand names, they prefer you to take generics over it, even if its a different type of generic.

Also insurance may have tiered system for certain drugs, the lowest being generics, the 2nd one being brand name of gernics, and then expensive generics would be the next tier, or brand names that dont have generics.

its when you get to things like biologics, or speciality drugs things get super expensive.

Ozempic addicts ruined it for people who need the drugs.