Also, people knew what was on TV before they turned it on.

People bought TV Guide magazine, which was pages and pages of listings, or looked at the TV page in the newspaper.

You also generally had the airtimes for your favorite shows memorized (I bet a lot of people who were alive in the '90s could still tell you when, e.g., Seinfeld, ER, The Simpsons, and The X-Files were on and on what channel number).