In addition to the other comment, there's simply a huge amount of format variation between local affiliates. Some are mostly music, often classical or jazz, with nothing else except daily news. Others are almost all in-depth news and programming like quiz shows and interview channels.

So there are places where the local station carries almost no NPR content.

Public radio stations across the US carry different programs.

After asking the question I thought about it more and I think I just need to fully commit to podcasts. I've pretty much stopped watching live TV (except for sports) and the same should probably be true for radio.