The reading thing doesn’t tend to surprise me, especially as I’ve gotten older. There are a lot of folks that have cruised through life without reading important pieces of literature, so I don’t tend to be surprised when I ask if they’ve read X and they say no.
Movies, on the other hand, are a modern phenomenon that does surprise when someone hasn’t seen a classic blockbuster. Star Wars? Blade Runner? Any iteration of Star Trek? These are so ubiquitous and culturally ingrained that it’s surprising when someone references one of these (or others) but hasn’t seen it. “Game over, man! Game over!” “I love Aliens!” “Never seen it.”
There are classic bits of cinema that I think everyone should have seen, but I rarely expect them to have.