The argument for having insurers cover routine care is that prevention is cheaper. Ideally insurance companies would gladly pay for that since it would save them money in the long run.
The problem is that companies are penalized for long-term thinking. Why pay today when in the future it may be someone else's problem. That creates a sort of tragedy of commons among insurers. No one is insurer wants to pay today, but everyone would be better off if all insurers paid. That's a known market failure so some government intervention is necessary to improve market efficiency.
Unfortunately healthcare ticks a lot of other "market failure" boxes in its mode of operation. So it needs to either be heavily regulated or socialized to prevent market failures driving prices up and efficiency down. Don't believe me? Ask any economist that studies market failures.
The problem is that companies are penalized for long-term thinking. Why pay today when in the future it may be someone else's problem. That creates a sort of tragedy of commons among insurers. No one is insurer wants to pay today, but everyone would be better off if all insurers paid. That's a known market failure so some government intervention is necessary to improve market efficiency.
Unfortunately healthcare ticks a lot of other "market failure" boxes in its mode of operation. So it needs to either be heavily regulated or socialized to prevent market failures driving prices up and efficiency down. Don't believe me? Ask any economist that studies market failures.