They do ask a Priest for forgiveness who then "absolves" them of their sin. Instead of asking God to forgive them of their sin in effect circumventing God and instead giving that power to a mere man. This is so the Church can control their constituents by claiming only the church leaders have the authority of interacting with God. With no where else to turn, as it is an established tenet of the church and is firmly reinforced by church teachings they must remain loyal or suffer the wrath of God for unsolved sins. This includes pentinance for the sin established by a man, includes fees from approved and often unapproved Papal authorities which are often forged so local Dioceses and Priest can sustain life styles of the rich and famous