You’re pretty angry for someone who has limited knowledge on this topic!
It’s highly subsidized by the gov’t so the fee is trivial compared to the benefit. 2019 budget is $99B. Monthly cost is a little over $200 if you pay full freight.
Unless you’ve got other insurance, you’d be stupid not to go with Part D. You’d pay more with a private plan.
Medicare Part D plans (private insurers) compete for customers and get money from CMS for offering coverage that confirms to CMS standards.
It’s far more than “negotiating block and cost averaging”.
Single payer needs to happen, now. Medicare for All.