Owners also have a lot more time to notice all of the stuff that's not quite right. The cars with touchscreens for example all have an absurd number of weird, sometimes very annoying, software bugs that come up in edge cases or only occur intermittently that you probably wouldn't notice if just taking a test drive.

Few car owners spend a lot of time thinking about the stuff their car didn't screw up or have a good basis for comparing those to a wide range of comparable vehicles.

Reviewers are also usually biased towards reviewing products that are good and/or interesting, and while that's also true of consumers, you'd expect reviewers to be more informed.