What do you think would be different between 25-year-olds and elderly people? The incentives are the same in both cases, produced by the billing code.
I think there is also a matter of what you view as 'necessary medical care'. Preventative medicine is vastly cheaper (and more effective) than reactive procedures to fix things that have become serious issues.
(It makes practical sense, right? You properly maintain your roof so it doesn't leak, that's cheaper than fixing the damage caused by the leaking roof).
This is particularly true with older people who have higher incidence of cancer, heart disease and major organ problems.
So yeah, they may send you for a battery of tests that they can charge the state for, but it might be preventing a much more expensive (and traumatic/painful) surgery down the line.
But people seem to focus on the collective bargaining and price aspect of everyone having proper healthcare, which is weird because it shouldn't be about that, it should be about increasing the efficiency of the overall system and quality of life of the people involved.
There are more things to check because older people have more medical problems, therefore more tests, more treatments, etc.
We would have to see what would happen if you gave a 25 year old medicare in this country, I doubt it would be the same experience that an elderly person would have.