I am a glasses wearer full stop. My day to day pair are photochromic but not polarised. Even this week in the rain they have darkened to a noticeable degree when I've got back indoors, but it doesn't take off the glare or that little bit of dazzle.
I will often wear my clip on polarised sunglssses when cycling, walking or driving in less than glorious sunshine as I find that taking the extreme edge off what brightness there is assists me more in seeing wirh total clarity than does having a slightly darker view that my pupils dilate to accommodate anyway.
Everyones eyes and response to the light hitting them is different. I'm sure some do it for the look but for some of us its genuinely done to help ourselves.
P. S. Even on the roadie I'm in jeans and t-shirt but still often with the dark clip on's on.
Also these people that amuse you may be out for an all dayer and we all know that you can often get four seasons in a day here, better to be over prepared than under.