Art in bristol

It seems as if everyone is jumping on the graff/bansky scene which is good as we need it however if bansky can get away with street art and no fines etc... then why is it my friend who has just been to court and was in the evening post for doing the same thing has a huge fine and is being put on tag ?? the council is even cleaning banskys work ?? most likely using my friends fine payments and my tax money ... crazy