If car insurance had to cover a 6+ figure operation replacing an old engine that was was seized up because of poor maintenance, it would make financial sense to cover oil changes as a preventative measure.
A health disaster is several orders of magnitude more expensive than an automotive disaster, and you can't just total out a human being and pick up a new one at the local dealership if it's too expensive.
Preventative maintenance is a money saver long term.
"Annual physicals" in asymptomatic individuals are known to be a useless waste of money and time.
https://sciencebasedmedicine.org/re-thinking-the-annual-phys...
By that logic car insurance would cover brake service.
Human error causes >90% of car crashes (https://cyberlaw.stanford.edu/blog/2013/12/human-error-cause...), so brake maintenance is a very inefficient way to reduce insurance risk. Instead, insurers penalise people based on their history of crashes (or — more importantly to the insurers — claims). The market is actually working well in that case.
Going to the doctor for an annual physical is not something that should be insured. It's a known cost. You, as the individual, should pay that out of pocket, or get another extended coverage policy or rider to covert that. It's like my auto insurance paying for oil changes.
As a result, our costs are too high.