I got a cold yesterday with a crazy bad sore throat, I thought of maybe popping into the doctor. But it turns out to be just a regular cold. My mother would have 100% gone to the doctor. The clinics here in Canada are chock full of kids with the flu and people coming in 'because'. Maybe that's beneficial due to the risk 'it could be something bad'. Or maybe the economics don't make sense i.e. for really mundane things it's better to just stay home and take Tylenol.
But the demand is super high. Once people cross 50, there are always problems. Always something. And it's all expensive.
Assuming the average doctor’s visit is 15 minutes and the average person goes to the doctor every month. That’s only 1 GP per 640 people. After that point they might send you to a specialist some fraction of the time, but it’s still finite.
Consider dental insurance is ~15$ a month and most people go to the dentist twice a year. That’s about what GP side of heathcare costs. It’s the care after that point from people with actual issues that gets expensive. Yet, without the vast overhead of insurance you cut the costs of providing actual heath in half. Which more than covers the costs from people that are currently turned away.
PS: And yes billing is ~50% of current US costs when you include Doctor time dealing with paperwork. Remember the entire insurance industry and their profit is pure added cost, but so is the medical billing people inside each provider.
I would assume it's detrimental because it results in doctors' waiting rooms full of people with colds (making it a dangerous place for anyone who is immunosupressed and really needs to see the doctor).
In reality most healthy individuals want a limited amount of care, sick individuals want the least amount of care required to return them to health - and there are fundamental limits on the amount of care that can be provided to those who are beyond the help of current technology.
As such you would expect a finite level of demand from the economy as a whole if everyone was allowed as much healthcare as they desired. Any attempt at rationing care will both reduce efficiency, and constrain supply - driving up prices. The most market oriented system would leave supply unconstrained and provide universal and automatic coverage allowing more suppliers to enter the market until supply outstrips demand and "prices" naturally fall.