I am sure, at this point, for some people the tests don't work. I have lupus and take immune suppression medication and my only means of transportation is public transport. Normally, I collect every germ possible. But somehow not COVID? Nah.
For me, the vaccine seemed to prevent catching the first few variants quite well, but i eventually caught the Omicron (probably, idk for sure) variant. My SO showed symptoms first, and neither of us tested (nasal swab) positive until ~24hrs after symptoms appeared.