Does it matter how you treat a stranger you will never encounter again – like the person riding the bus, the clerk at the grocery store, or a fellow driver on the road? You will not likely face direct consequences if you are mean to someone or cut them off. So, does it make a difference how you choose to act?
Judaism, in particular, and religion in general, teach us that our actions matter greatly. Judaism built a whole system to assign importance to all of our actions: from the food we eat to the blessings we recite, and to our treatment of others. In Tazria, we see one manifestation of the consequences of our actions. The rabbis of the Talmud believed that people became infected with the skin disease tzaraat as the result of a spiritual sin. A person might physically bear the mark of a misdeed until properly repenting.
I do not believe that people’s health conditions are punishments from God. What I take from this portion is that our actions have consequences – even when we imagine them to be victimless or unimportant.