As well as the sister comment mentioning distance driven as a relevant metric, some other aspects to consider are — if they only have a smaller ratio of car owners, I'd suspect there are less "car only" roads like motorways. Roads in city centres are also shared with a much higher ratio of foot traffic or people on bicycles/rickshaws etc.

The relevant metric is distance driven.

Micromorts per 1000km.

A micromort shouldn’t be confused with a little death. They are very different.