Actually it's not always entirely up to Page or Led Zep! Keep in mind that the first two albums Zep released were involved in legal issues over Zepplin sampling music from others thus the licensing is not Zep's to give. If you have an original copy of LZ first two albums you will see that Page is credited with writing a lot of the songs but if you buy a CD today of these same albums the writing credits have all but been removed. This was part of the agreement when the lawsuit was settled!