It's an odd framing. Out of R_t total raccoons, R_e bite or scratch (potentially "expose") humans. R_e / 10 of those were carrying rabies. So it could be that raccoons almost never bite/scratch humans, such that the behavioral effects of rabies are a significant motivator. It also could be that raccoons bite/scratch humans all of the time, and a ton of those raccoons have rabies. The latter is scary, but the former is likely the truth.

I wonder if increased interactions between humans and raccoons will lead to a reduction in that 10% figure (more reasons to bite humans).

It's that it's not 10% of racoons have rabies, but 10% of the ones that expose people to a bite scratch etc. The reason the numbers aren't the same, significantly less than 10% of them have rabies, is mainly that rabies itself can make them more hostile etc., on top of if bitten by a racoon that is more symptomatic seeming you are much more likely to get it checked out.

An “exposure” in this instance to rabies would be physical contact - a bite, scratch, or from its saliva on an open wound for instance.

you would think that 100% of racoons that expose people to rabies have rabies.

I think the idea is that a raccoon you encounter is conditionwlly more likely to have rabies just based on the fact that you've encountered it. My understanding is that rabid racoons are less nocturnal and far less likely to feel the need to run or hide from humans.

It's possible they botched the grammar here a little, but my interpretation is saying that if you look at the group of raccoons that allow themselves to be exposed itself to a human or pet (rather than avoiding us, which is not that hard for them to do it they want), around 10% of them have rabies.