BBC article on cycling accidents

My point is that 8 HGV fatalities is not the sample, it's a set of observations from a larger sample, or pair of populations, men and women cyclists, where the available observations are 'Died by HGV this year' or 'Did not die by HGV this year'. Clustering doesn't come into it.

Clustering does come into it. Even if we look at fatalities in general it's still a small sample. You mention people knowing nothing about probability theory but one of the main principles about extrapolating probability is that you can only predict future events from very large groups of numbers. It's the Monte Carlo fallacy.