What's weird about health insurance in the US is that it's often tied to an employer, and you can't freely switch between insurance providers on a whim. It's a way worse experience than insuring a car, which can be done on a phone in a few minutes.
In effect this is how home appliances are regulated. You have companies like ETL Intertek and Underwriters Laboratories performing fire and electrical safety testing of home appliances, originally on behalf of homeowner's insurance companies(See the definition of "Underwriter"). It's effectively self-regulating because the Intertek or UL stamp implies a certain degree of care. And based on some lease provisions I've seen the insurance companies for buildings do require use of certified equipment as a condition of coverage in many cases.
Auto insurance doesn't pay for your gas because they don't have to pay a claim if you run out of gas.
This is often repeated, but it's simply not true. Preventive care is better for patients in the long run, but at a population scale it is more expensive than foregoing it.
And that is before you account for the fact that patient churn is quite high (especially since most plans are linked to employment). An intervention that cost money today and may increase costs within the next few years (due to followup care) is much more expensive for insurers if the savings will only be realized in 10+ years, when the patient has moved on to another job and so is no longer on their plan.
Very few medical interventions save money in the short- and medium-term at a population level. That's reflected in the fact that health insurers didn't cover most preventive care until required to by law (the ACA), and even then they routinely simply ignore this provision of the law. If it were profitable for them to follow the law, why would they go out of their way to break it?
Take, for example, PrEP for HIV prevention. Costs about 5,000 dollars a month - insurance is forced to cover it. Sure, you could say HIV is very expensive, but few people at risk of HIV actually get it. If it were up to insurance companies, they'd rather just pay for HIV treatment or even better - just drop customers with HIV. The ACA prevents the latter, and the former was the case for 15 years since Truvada was introduced. Of course, now that's changed too, and they have to pay for Truvada.
Except, many (most?) insurers straight up ignore this requirement and charge people for PrEP, even though it's illegal. The ACA is very clear that preventive care is required to be covered in full with no cost-sharing or out-of-pocket cost to the patient, even if the deductible has not been met.
https://kffhealthnews.org/news/article/prep-hiv-prevention-c...
Granted, the comparison is imperfect. Medical insurance won't pay for a healthy diet (another way to reduce health problems) and replacing the brakes on a car would reduce the chances of an accident causing thousands of dollars of damages ... but we are human, and sometimes it is a miracle that we even take half measures.
But it's not weird that the insurance company wants you to get a flu shot or exam, since those things prevent them from paying out more money later.
In reality there is some cross over point, where the flu shot isn't worth it for younger people, and is for older people. If you are young/healthy, get the flu and totally recover with a few Tylenol, and no insurance claims, then it clearly wasn't worth a $10 vaccine to prevent. That's the analysis for the insurance company. Depending on how you value your time, and time spent sick, your individual analysis may be different.
Health insurance is new, because until the 1920s/30s the salary loss from sickness was more expensive than medical care, so that's what was insured against.
But no sooner was demand for health insurance created than it was pushed into groups. In America, there's never been a time where non-group insurance was the norm.
The reasons is clear: healthy people would not get coverage, but sick people would.