https://en.wikipedia.org/wiki/Subtext
Lots of people aren't, so it's not uncommon to see people whose appreciation of some works never gets beyond the surface level.
And sometimes they're so inattentive that even the text itself is lost on them. My standard example of that is Bruce Springsteen's song "Born in the USA," which is widely understood (in America, anyway) as a bombastic, "we're number one!" patriotic anthem, played at political rallies and sports events and the like. If you pay attention to the actual lyrics (http://www.elyrics.net/read/b/bruce-springsteen-lyrics/born-...), however, it's clearly a song about how the American system screws the little guy. But most people don't listen beyond the upbeat, poppy chorus, so they miss Springsteen's entire point.