I think that's exactly it - the rate of gun/traffic deaths is relatively constant, all the way out to 85+, but as people age into health problems, the relative number of gun/car deaths gets reduced by non-injury deaths. You can see that in the lower graph, and it's really interesting to me how the different presentations focus my attention differently. The top figure makes me think that cars, guns, and drugs are a huge problem for people under 40-50, but the lower figure makes me focus on diseases of the elderly.