I'm interested in the apparent intolerance of shirtless men, I didn't realize that was a thing.
India has certain public decency laws which prohibits exposure (not sure if shirtless would qualify), PDA, etc.
India is also famously not one of the fitter countries - so it's also a matter of body image issues.
Not sure about India but in a lot of European countries walking shirtless on the street might be a fineable offence. A larger discussion on the subject can be found on this recent /r/europe thread. [1]
[1] https://old.reddit.com/r/europe/comments/qixnsa/filling_up_a...
Parks, beaches, saunas it would of course be normal.
But out in public, the only men w/o a shirt would be those who are too poor to afford one or those who are poor, doing manual work and who want to get rid of their shirt on a hot day.