Would a perfect God do this?

In the book of Deuteronomy it clearly states that an unmarried woman who is d is to marry her rapist, and he is to pay her father 50 silver shekels. I know this was to protect the woman from being used and unwed forever. Wouldn't a merciful and fair god just tell people that a woman who is d is not damaged goods? This question is not "should we obey the old testement?" So, please don't go into that.