Politeness OTT

I've noticed a rather weird behaviour going on during the lockdowns to do with social protocol whilst walking outside. Several times now as I've approached people coming in the opposite direction, one party or the other takes a few steps to the side either onto the verge or onto the road, as appropriate. Sometimes it might be me and sometimes it might be them, usually depending on who spots who first etc. Several times now I've had people murmur something as we pass each other, the phrase they utter is a sarcastic "you're welcome" as if to say "you should thank me verbally for slightly altering my course for you". 

Now, I'm all for politeness in our dealings with one other and if someone jumps into a muddy puddle or a in order to get out of my way (unasked!) then of course a subtle nod of the head or even "thanks" is utterly reasonable, but if we're to thank everyone who takes a little side-step to maintain social distance or expect one in return then we've probably gone a little bit far down the "Victor Meldrew" path. I'm reminded of the scene in Crocodile Dundee (the first one) when he goes from the Outback to New York for the first time and is walking down a crowded Manhattan street trying to say hello to everyone he passes them, i.e. completely OTT. Rather than being nasty to these people I've decided to respond sympathetically and compassionately, I simply reply with the words "mental health", hopefully they stay even further away from me or perhaps seek some professional help.