I don't claim to know for sure, but it seems to me like the reason for that is because all of these laws are restrictions are companies trying to do shady stuff to sell you more then what you wanted. Allowing the person purchasing the goods to keep them as well as get money back encourages companies to not break these laws since they don't want to lose their stuff. If they got their goods back then there really wouldn't be any repercussions toward the company for breaking these laws since the transactions would (presumably) be cancel-able within a specific time-frame already.