That's interesting, I don't generally think to myself, "Hm, I could go drive around for an hour or I could go for an hour long walk", I usually think "Hm, I could drive to this place or bike over there (I don't usually walk)". Although I also don't really think about the risks of everyday activities anyway, so who knows.

It's really difficult to compare the risks of walking vs driving since usually they aren't really interchangeable and they have such different use cases. But the original comment was about running a marathon vs driving the same distance.