[root_axis]

> I have never come across a piece of debris so large that driving over it would damage my car

More likely you simply drove around the debris and didn't register the memory because it's extremely unlikely that you've never encountered dangerous road debris in 30 years of driving.

[foobarian]

I think it's probably because of mostly driving in enough traffic that other cars would have encountered any critical objects first and created a traffic jam around an impassable section.