Don't be naive. Medicare reimbursement rates are artificially fixed below the market rate in order to hold down the federal budget. This kind of works right now because Medicare ends up with a hidden cross subsidy from commercial health plans with higher rates (often explicitly set as a fixed multiple of the Medicare rate). If we put everyone on "Medicare For All" then those subsidies will disappear and queues will get much longer. So not everyone "gets" healthcare if they have to wait a year for an elective procedure.

Also, original Medicare Part A/B doesn't cover certain types of healthcare at all such as prescription drugs. So not everyone on Medicare "gets" healthcare today. That's why many Medicare beneficiaries choose to pay out of pocket for Drug Coverage (Part D), Medicare Advantage, and/or Medicare Supplement (Medigap) insurance.