Your car engine doesn’t store information about everywhere you go and what your interests are.
Your car engine probably doesn’t experience data leaks, social engineering, or 0 day bugs.
The argument is Google and Facebook don’t 100% know their data usage and risks and I’d agree that’s true.
Complex software systems are impossible to 100% guarantee expected behavior. This is why bug bounties and the security industry exists.
The safest way to protect information is to not store it, the second safest is strong encryption.