I would expect that the vast quantities of helmets available post war was simply due to the fact that nobody needed them anymore. While hostilities continued, I expect the demand for quality head protection was quite high.
I do agree with your point that inferior helmets weren't in demand during the war.
To me the thread starter helmet looks like a foresty workers lid.
Good point re postwar
I collect, therefore I am.
Nothing in science can explain how consciousness arose from matter.