The author not only correlated the increased number of deaths with the increased number of large vehicles around, but also found that there is cities with larger increases in vehicle size had a correlated larger increase in deaths. So essentially there is a correlation on different levels, which is a much stronger indicator for causation.

If you are saying this is a spurious causality you should suggest alternative reasons why we should see the correlation. To me it doesn't seem that there should be any reason why cities with increased vehicle sizes should also have increased number of people walking on the roadside without sidewalks.

Moreover considering the large numbers we are talking about i would imagine intoxication for example would average out.