"Another poster complained that walkers don't notice runners coming up behind them, are we supposed to walk backwards?"
You're supposed to look around you from time to time. I've lost count of the times I'm running and can see half a mile in front of me, and the pedestrians (or more often, two pedestrians taking up the whole path) don't look around once. Just bumbling along in the middle of the path, usually with headphones on. I cross the road if possible and run on the other footpath, but if I can't cross then more often than not I have to run into the road. But runners are the selfish ones.
I wait. I stop. I move in to mud or the road to give people space. Walkers never do that.
All these pedestrians complaining they're being brushed up against on a footpath. If there are two of you, one keeps to the left and one keeps to the right. What is the problem here? No need to brush past anyone, so the only way that's happening is if the pedestrian isn't on the right or left. Or the runner is sweeping over from a space on a pathway to deliberately brush past them. Righto.
There are arsehole runners. Arsehole pedestrians. Arsehole dog walkers. But I can tell you as a seasoned runner that the number of arseholes has risen during Covid; so I can't wait for things to get back to normal because half these people won't be seen shortly.