You'd be suprised how selective some people can be (especially people with a good memory who often avoid cluttering with stuff they have no use for and aren't curious about). Seing things all around and memorizing them, especially for long term, are two different things. I hang out with a few scholarly people absorbed in their work or hobbies who would demonstrate what you'd call an appalling lack of knowledge of mass market culture.

I'm not especially scholarly (nor ignorant of pop culture I care for) but I'm pretty sure I manage to avoid any knowledge of the majority of the "blockbuster things" and TV shows (eg: I know Castle is a TV show often discussed here, don't ask me who's in it or what it's about, not even its genre), despite commuting, despite reading the papers and trade magazines and much worse, despite working in the field. What doesn't interest me I manage to ignore or forget about really rapidly. It puzzles friends sometimes that I remember minute details of the stuff I care for, but that I manage to ignore that the Green Lantern is a superhero, to give you a real example that happened in a discussion at work last week. I remembered distinctly the circumstances in which we worked to adapt those ads in French and could tell you what the graphic elements looked like or how they were animated, but about the movie underneath, nada. What has not registered about American superheroes before I was 10 I know basically nothing or extremely little about as they bore me and I stay away from that sub-culture (eg: I was told about 6 months ago that Dr. Who isn't one of those but a british SF character - then I noticed the trailer for that show on a Spook season on DVD that I had watched a few times before). A lot of blockbusters I know about because I've borrowed the DVD from a colleague or friend to screen in fast forward, stopping only to watch the VFX sequences.

As for pop music, it's much worse. I don't think I could name any American or Brit pop singer or band that's very popular right now. I'd probably know of a few if people give me names, but out of the blue I can't think of any, except Lady Gaga (and it's the same for most of those from the last two decades, to be honest. I watched an episode of Glee with Britney Spears a few weeks ago. I knew the name from various jokes about scandals or some such over the years, but didn't remember hearing any of those songs before). And it's not that I don't listen to a lot of new music.