syag, common, you are discussing some complicated and rare cases. I am suggesting to look at very simple, very basic fact: most people who were careful did not do anything bad, did not snitch, etc. Most people who were not careful put others in danger.
I do not understand what exactly is Syag challenging. There are obviously multiple random events leading to someone getting sick, but what is so difficult in the idea that the more someone who is with some chance having a virus being uncareful in presence of others leads to the other illness? Torah does not disagree with basic statistics and lots of Talmud considers effect of one’s actions on other people. Maybe you can clarify.