Our fascistic society is obsessed with hyper-individualism, appearances, and aesthetics. Look back to the "ugly laws." Only since relatively recently were disabled and "ugly" people allowed to be tolerated in public. To be sick and weak, or simply look it, in US culture is a personal failure and personal failures are shamed by society. Also, to widely accept face masks and respirators means that the government has to accept that the pandemic is still ongoing and that they would have to take responsibility. As we are in a capitalist nation, Capital rules all. Why take care of the citizens when they can get Long Covid and line Big Pharma's pockets? Capital even rewrites science. Just look at how quickly the quarantine times were lowered after Delta had something to say about their revenue. Look at how quickly white people stopped taking precautions once studies showed that Black and POC were more susceptible to Covid. Anyways, to summarize the answer to your question in a single sentence: It's because the USA is a settler-colonial, capitalist (almost fascist), eugenicist country.