Comment by bruckie

That indicates real increased risk, though, compared to someone who drives in places where animals are less likely to be in the road.

Insurers aren't trying to determine how good of a driver you are (conditional probability of you being in a collision given conditions). They're trying to determine how likely it is that you're going to be involved in a collision that results in a claim (unconditional probability of you being in a collision). If you frequently drive through deer infested forests, it seems reasonable that your insurer is going to expect more claims compared to someone who doesn't do that.

It's similar to how driving late at night results in higher premiums. You can be the same good driver at night and during the day, but if you're frequently driving at 3 a.m., you're a higher risk.