Medicare expenses will overwhelm the US budget and create unaffordable deficits unless spending slows down.
Most Medicare recipients don't have any out of pocket expense for any service. They buy fairly expensive co-insurance that covers the 20% copay that Medicare requires as well as the $130 deductible. This results in overspending by the Medicare recipients. A small copay would cause some hesitation and slow down in spending but not be enough to keep the Medicare beneficiary from receiving services they really need.