Where I lived (France), people are generally dressed correctly in churches. Many churches are ancient ones in stones and fresh in summer. Not always, but in general yes. It is not the case in all europeans people/countries. Sometimes climate and hot concrete churches can be a partial explanation (Spain), and sometimes not, there is a cultural gap (Holland and Northern Europe for eg).
Your need of wearing shorts in churches is understandable. Like myself, when I have to ride up some of my clothes because I have to breastfeed my children. It is that or my family have to miss mass for years.
When I see people with lights close I don’t think it is frequently because of an imperative like yours.
What made me particularly angry is when I received, for youths catholic gatherings, a notification from organizers of a dress code counseling strongly people to wear cropped trousers versus short and tee shirt with short sleeves vs sleeveless top, because we go to churches. Quite normal. But when we are there, the same people who send us the dress codes, wear shorts and sleeveless.
I know that I judge people, but it is dificult for me, to not have instinctive reactions.
And that’s probable that I would have judge you if I had seen you in Churches without knowing you.