This was partly to teach them that all souls are of equal worth in themselves and price with God; that there is no respect of persons with God, and in God's worship and service, but gospel graces, ordinances, and privileges are common and equal to all, Exo 12 16:18 Galatians 3:28 Colossians 3:11; that all persons are alike obnoxious to Divine justice, and are redeemed by one and the same price: partly to check the arrogance and vanity of the rich, who are very apt to despise the poor; and partly that by this means the number of the people might be exactly known when occasion required it.
Related Commentaries of Exodus 30:15
Exodus 30:15
15 The rich shall not give more,f and the poor shall not give less than half a shekel, when they give an offering unto the LORD, to make an atonement for your souls.