22-year old single, marathon runners pay the same rate as a 37-year old, single, lazy, 300lb HackerNews commenters.
That and the fact that routine care/services are "paid" for by so called "health insurance" is why it's bogus to compare it to standard insurance.
Health insurance sold on a group basis is underwritten on a group basis. That does not have anything to do with whether it is "real insurance." Health insurance sold on an individual basis is underwritten on that basis, but rate differentials may be severely constrained by statute or regulation.
These do not affect whether financial risk is transferred. The routine care issue does impinge on a valid consideration of whether the transferred risk is "insurable", but since these are short-term contracts it is not fatal.
What would those policies cost if they did?
The better comparison would be with Worker's Compensation insurance, where the loss control mechanisms are ongoing.
As far as what the policies would cost, I don't know. Even if routine medical care is fully covered, a lot of people won't take advantage of it for whatever reason. An insurer's actuarial models will build that expected frequency into the projected cost.
If it bothers you sufficiently, you may consider most health plans to be the sum of a "real insurance" policy and a routine health discount plan. There are health plans that truly avoid assuming substantial risk, although they do so by getting providers to assume the risk. Those plans do retain the risk of providers in their network going bankrupt where prepaid capitation would be lost.
Employers pay those costs themselves in return for rate reductions. Not sure how that differs from any of my other comparisons (auto, life, homeowner's).
I think you have to admit that one's health care premiums have nothing to do with that individual's "actuarial" risk to the insurance company. There is not a single form of insurance that follows that pattern. NONE.
As for the other, I admit health care insurance has its own peculiarities that make it a distinct field of insurance. And, no, your last assertion is incorrect. I have the advantage of having actually worked in the group pricing department of a major health insurer, so I'm not just speculating here. In lieu of further banging my head against the wall, I'll point out that the syllabi for the SOA's actuarial exams are available to the general public - just look in the "education" section of their site.
You obviously don't understand insurance outside of healthcare, if the insurance companies' underwriters and actuaries do their job right - the profit/revenue of all policy types is the same regardless of risk.
High risk=High rates, Low risk=low rates. Revenue/risk is balanced.
We all suffer spiraling healthcare costs because there is little correlation to what you pay for healthcare insurance and your overall risk to the insurer.
"Group underwriting" only exists in the healthcare industry - no where else.
Every rational form of insurance relies on distributing risk over groups of independent risks to obtain the benefits of the central limit theorem. There are some very specialized policies, and the Lloyd's syndicate, but anyone wishing to avoid ruin will diversify their risk.