Since you are asking about the universe, not specifically the movie, I would say they read manuals. We know that there is some writing in the book because we get told that there are written "scripts" comprising "lines":
She didn't look up from her script again. "Well, this is a play comes
on the wall-to-wall circuit in ten minutes. They mailed me my part
this morning. I sent in some box-tops. They write the script with one
part missing. It's a new idea. The home-maker, that's me, is the
missing part. When it comes time for the missing lines, they all look
at me out of the three walls and I say the lines: Here, for instance,
the man says, `What do you think of this whole idea, Helen?' And he
looks at me sitting here centre stage, see? And I say, I say --" She
paused and ran her finger under a line in the script.
("She" being Mildred, Mondays wife). So we can assume that the technical stuff might also be written down.
I guess the movie has excised that bit because a world that has done away with Balzac and Shakepeare while retaining technical manuals and the script for Jersey Shore might possibly fail to elicit the kind of shocked response the director was after.