When I took early retirement, I paid around $1000 per month for a 5000 dollar deductible and had no drug benefits. I have no complaints about cost of Medicare to me - it is a bargain.
Companies are by law required to subsidize about 50% of the cost of health insurance they offer employees (not sure if ACA changed that percentage). So the answer to your question is related to what the Employer is doing.
Now I pay around $300 per month for Medicare A&B, Supplement F and Medicare part B. The F supplement is from Mutual of Omaha, and that was the cheapest price for the exact same product.
The Mutual of Omaha agent reviews the Part D program and informs me once a year what’s available and potential cost for the meds I take on a regular basis. My copays for three different meds this year: $1.20, 6.83, 8.50 per month. So far my copays plus part D premiums are essentially equal to what the drugs would have cost with out the plan.
My pharmacy will only charge me the cost of the drugs-ie cost basis, when that is less than the insurance co-pay.
In general, I refuse to take “new” meds. I prefer generic, or OTC, because the side effects are well known and documented. That also helps me to keep my costs low.
IIRC, Medicare is not allowed to negotiate prices with the drug companies, but private insurance does. Medicare does dictate what doctors and hospitals will be paid for services.
They often pay less than 50% of the amount billed. This contributes to a shortage of doctors accepting Medicare, and also means that those who do accept it, must make up the difference in the individual market.
Medicare premiums after age 65 are a real bargain. Private Insurance would have adjusted these prices upwards a long time ago. Private Insurance is by default subsidizing the current outgo of Medicare payments for treatment. The Employers are subsidizing the cost of insurance for their Employees.
The individual who has to purchase a plan directly, and the person with no insurance are the ones that experience a huge discrepancy in cost, since they are not subsidized, and cost shifting described above.
I am very happy with the cost of my Medicare insurance and co-pays. I repeat - it is a bargain.
My mother uses F from Mutual of Omaha also, and it works well. I hear that all F supplements will be discontinued before I turn 65 in three years, unfortunately.