In Exodus 30:15, the children of Israel are commanded to pay the half-shekel to ensure that their enrollment in the census will not bring to the people any nasty consequences such as plague, which is mentioned by the Torah here. Thus comes the frowning upon the counting of Jews and the numerous ways invented to go around this superstition.
However, more interesting is the Torah’s demand for equality here. Both rich and poor have to pay the same amount of money regardless of their income. “The rich should not pay more and the poor should not pay less”, says the text. Chizkuni comments on this, “if the Torah were to allow the wealthy to contribute more and the poor to contribute less than a half holy shekel each, how could each of them attain the same level of atonement? “.
Nahmanides goes even further and lists this commandment as one of the negative commandments of the Torah. The atonement should be equally reachable for everyone. No material circumstances can ever hinder the person’s way to forgiveness after the transgression or, which happens more often, can assist the person to receive this forgiveness before the others could.