Women covering their hair

Question

some women get custom made wigs- meaning wigs that r others people's real hair. so why is it that we can show other people's hair and we cant show our own. i mean when a women gets real hair to cover then they r showing someone elses hair but they cat show their own? and how is it that lest say a women who had long hair and wants to cut it and make it into her own wig and she is aloud to. technicaly she isnt really covering her hair. is there and explanation?