Pushing hard can make you a bit tunnel visioned, but for injury's sake it's not a great idea doing that too frequently anyway, and the general puffing like a steam train gives advance warning of the approach, and the glazed beetroot look is another good give away. 
The bigger issue is that there is more than a fair share of arseholes in the world and they tend to turn up in most activities going. It's easier to remember the arsehole runner than the 5 that were pleasant and responsible.
My bigger issue whether I'm running or walking is the superglued couples or socially distanced family groups occupying the pavements in relentless formation. I have passed these within 2 metres because I'm blowed if I'm going knee deep in the undergrowth or down the white line of the road to avoid a dick who won't pull in another metre or so when it's perfectly possible.
Please bear in mind that when a runner moves into verges (especially those that have not been cut yet and the long grass is obscuring dips, humps and litter) that they are risking trips and twists/ sprains, more so than a walker.
It has been (depressingly) enlightening to discover that some walkers believe that runners don't belong on pavements and are obligated to give way to walkers (doubly tedious as some move unbelievably slowly-often not to do with invisible disabilities although that's not possible to conclude individual by individual).
The world is a better and happier place if we all mutually look out for eachother at whatever speed we travel at.