It's akin to other common courtesies such as covering one's mouth when sneezing, helping someone open a door or not playing with oneself in public. People who don't care about others are making their world view known. IMHO, they are proving to either be completely selfish, in denial and/or stupid.
FWIW, I go out once a week to shop and use precautions. Most of it is food but I did make a pitstop at Home Depot for my trailer project after a dental appointment to check a crown. They took my temperature using two different devices and I tested 99.9 degrees. I hadn't been feeling 100% since getting up that day, only about 90%. I had a constant minor headache which aspirin mostly relieved to the 90%ish level. Last night I had the chills. Today I feel better, but still less than 100%. It could be something else, but I'm content to stay at home, check on my wife and see what happens.
Most inside HD, including abou half of employees were not wearing masks. Fine. Without a vaccine, I think most of us are eventually going to be exposed. I haven't been tested and have no idea why I'm slightly under the weather, but am glad it's pretty minor whatever it is. I'm more worried about my wife, but, so far, she's a little under the weather too but mostly ok.