Do insurance companies actually pay full price for these drugs? I was under the impression that (at least in the US) it’s a bit of a racket where the bill will

Do insurance companies actually pay full price for these drugs? I was under the impression that (at least in the US) it’s a bit of a racket where the bill will say $1000 and insurance will make a deal with the supplier to pay $100 (while simultaneously telling you they saved you $1000).