Some just find spacial awareness a particularly distant concept. I posted a reply the other day in the 'runners in DP' thread after last running through there on Tuesday, making a huge point of avoiding anyone I saw, having to detour to maintain at least 2-3m. It really isn't a problem if your eyes are open. I absolutely get that walkers find a panting human bearing down on them, intimidating - so, from one runner to another - it's exercise, not the Olympics.