Perhaps it was a function of growing up in the Pacific Northwest in the rain, but my friends and I liked to listen to the news (of course, we were most interested in sports and weather). And, no, we weren't all nerdy types or intellectual types either! Even those friends who were less inclined to watch television news certainly did so by their early 20's. It's quite interesting to hear others' differing experiences.
It was the same way in my hometown of Bloomington IN. Those of us that had family at Indiana University (students or employees) were more inclined to be news junkies -- especially in the 1960s and '70s, between Vietnam, Watergate, and the civil rights efforts. My friends that didn't have an IU connection weren't as concerned.
By the time I got out of college and moved to Chicago, the news was all about local (and NOT national) politics, and nobody cared much about anything else. While I was in college here in the mid '70s, few people cared much about anything at all, outside their own back yards. Apathy was king. Fortunately, that's disappeared for the most part.
But in the case of younger adults, they still don't care, just like 40+ years ago. No reason for any station or network to attempt to attract a target audience that will just not be there.