Just to nitpick, I doubt i could wear a heavy premium quality cotton tshirt in the current summers. I can barely stand a flimsy thin cotton tshirt...
I'm willing to pay extra for quality linen for those summers, except everyone lies and their linen can be up to 100% cotton :)
I really cannot handle very hot weather, it's nice for a day or two but a week of constant 30+C is definitely not my happy place.
To me it was trial and error, recommendations, and shopping at physical stores, and like I mentioned as well: it's time-consuming, frustrating, and I wouldn't expect a person not interested in this quest to be able to find good quality items consistently.
I think this reflects how companies are run in US and Europe, they don't seem to believe how different companies can be here, its not only about turbo maxing the owners profit.