If they did not know what his job was (and I find that incredible)

Why? My last doctor knew what I did for a living, but only because we discussed it in passing when I was being monitored for Chagas' Disease. He certainly didn't record it anywhere. My current doctor knows that I run a lot, do British Military Fitness and rock climb....but only because whenever I've visited him it's been because of a leisure activity-related illness.

Why on earth would it be incredible for a doctor not to know what someone did for a living?