Next step: Educating people about what the lines mean. You’d think that people would understand, based on an analogy with roads. But apparently not. Many people assume that just because they are passing someone on their side of the trail, that they have right of way on the wrong side of the yellow line. If oncoming riders have to veer off, so be it.
On the other hand, I encountered an older fellow who seemed to think that he was not allowed to cross the yellow line at all, even when passing someone and when there was clearly no oncoming bike/pedestrian traffic in the other lane. That guy tried to squeeze past me in the lane without crossing the yellow line. (I was running at the time.) It was a long straightaway. I could see that there was no traffic in the other direction for at least 100 feet.
Sorry. I just get a little grumpy about trail etiquette or the lack thereof.