In a sense, wasn't the choice to not negotiate drug costs itself the result of a negotiation? I believe the way it works is that health insurers and providers threaten to fund fear-mongering attack ads against politicians who support laws that don't like. The politicians cave and carve out rules for the industry.

So it's not that the Medicare drug care costs aren't negotiated, its that the chance for lower costs was traded away by Congresspeople of the past (many of whom aren't in office anymore) in exchange for campaign funds. Not literally a campaign fund check, of course, but countering an attack ad costs campaign money that they could be spending otherwise.