Considering Black Sabbath came from Birmingham, working class, loads of children...I would say they adequeting represent the spirit of punk.
We are not talking about silver spoons or private educations here people...
Musically, it is not really all that different, I am afriad to say. Metallica, Green Day, Ramones...
To set 'punk' at certain band or gig is silly. Joan of Arc was punk, Jesus too.
He is not Alone