Does your auto insurance pay for your defensive driving courses? Your homeowner's policy pay for additional smoke detectors? Your life insurance policy pay for a treadmill?
To some extent, they do in the form of a premium rebate, though it is unlikely to be large enough to be a substantial reimbursement for a single policy period - perhaps over the life of the policy the cumulative rebate might cover the up-front cost. I haven't worked in casualty, only health, so I can only speculate.
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.
Do the insurance companies pay for safety equipment or training in their customer's workplaces? No.
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.
They forego revenue in exchange for the loss control. It's economically equivalent. This is like those discussions of whether taxes that are charged directly to businesses are paid by the business or by their customers.
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.
"They forego revenue in exchange for the loss control."
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.
What would those policies cost if they did?