"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.
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.