Yup, you're missing something here. That something you're missing is called the core concept.
When you signed your auto insurance contract, you agreed to pay that outrageous amount of money in exchange for coverage for a list of specific types of loss or damage. But that contract came with a big long list of stuff that isn't covered, called the exclusions or loss or damage not insured, and you agreed to that too. On that exclusion list is stuff like wear and tear, gradual deterioration, inherent vice (look it up), faulty workmanship, mechanical breakdown and a few dozen other things.
There is insurance against breakdown, and it's called a warranty / maintenance agreement. It costs almost as much as auto insurance, but it too comes with a big long list of what it does and does not cover.
You need to learn how to read, and then you need to learn to never sign anything you didn't read.