Windshields should have been laminated back then (a lot of manufacturers were using it in the 1930s). It's oddly difficult to find when it was required in automobiles in the U. S. But in reference to the picture I'm pretty sure you're talking about, even if the glass were laminated it should have spider-webbed. I have no idea what would have caused what is in that photo. I mean, it could have been just plain vandalism that was blamed on the "mysterious" pitting phenomena.
I'm only seeing the one picture with that kind of damage (the first one); the other one has circles drawn around the pitting to highlight them, indicative that they're pretty small to begin with.