I also suspect that rural people with an overwhelming pneumonia might not get identified if they had anthrax. I remember early in the HIV crisis, that we were told that probably some of the young men dying of "viral pneumonia" were probably suffering from this disease (this is before the blood test) and had PCP pneumonia. At that time, PCP pneumonia was usually only seen in cancer pateints and in vietnam orphans. I remember my only case was a lymphoma patient with "viral pneumonia". We couldn't do the culture, so treated him and he got better.
Ditto for anthrax
I suspect that there have been Anthrax infections for years, and the good docs like you cured it with the antibiotics you prescribed for infections. The older and more fragile patients died of pneumonia from the agent, and as we know, autopsies are seldom if ever performed on elderly patients who die of pneumonia!