I'm under the impression that Bayes' theorem is included in the high school math programs of most developed countries, and I'm certain it is included in any science and engineering college program.

It was in my high school curriculum (in Italy, in the mid-2000s), but the teacher spent probably only 5 minutes on it, so I would be surprised if a nontrivial number of my classmates who haven't also heard of it somewhere else remember it from there. IIRC it was also briefly mentioned in the part about probability and statistics of my "introduction to physics" course in my first year of university, but that's it. I wouldn't be surprised if more than 50% of physics graduates remember hardly anything about it other than its name.