I remember seeing news broadcasters in the 90s that didn't know how to pronounce the '@' symbol. So while I find your story all too plausible, I have a hard time believing that people still don't know how to type an '_'.
I suggest that there are fewer people in this world that 1) know how to use a search engine, and 2) are incapable of examining their nice silkscreen printed keyboards, than you suspect. There is a world of difference between "uses it" and "capable of figuring out how to use it".