I don't have the stats you're looking for, but I would guess the prior probability of accidents and foul play in smaller communities is also going to be lower than it is for large urban communities, because these communities are more tightly-knit, and people drive less rashly to begin with, etc. Or maybe they drive more rashly - I don't know. The point is, there are a lot of factors to consider. So it's going to be hard to draw conclusions from stats.

In other words, how much of those numbers is explained by said lower probability, and how much by parents' willingness to trust their kids?