It's easier politically to blame corporations and whatnot. And it's true - there's plenty of leeching downstream by pharmas, PBMs, hospital admins, device makers, insurance companies, vendors, labs, and many others. But at the base of the supply funnel sit the doctors (and numerous associations like AMA, ACR, ABP, AHA, AAMC, etc) who control the entire supply through licensing and state-level regulations, and are entirely responsible for all of the atrocities. It's effectively a cartel.
There's a reason why any time there's a talk about pro-consumer regulation on the Hill like anti-surprise billing, pro-price transparency, and Medicare for All, each of these association is blasting their members with calls to contact their representatives and resist at all cost. Their argument is easy to understand emotionally - doctors will protect you from the harm, and hence there should be more licensing and supply restrictions. But this is the root of all problems in US healthcare.