How young is too young to watch Dr Who? Or LA Ink?

My friend lets her 7 year old and her 9 year old watch Dr Who..it seems young to me...it is scary and violent...I would not judge others but this same person was shocked and pulled thi judgemental face at me because I let my 6 year old daughter watch LA INk sometimes as a treat. She loves art and colour....she is interested in medical stuff too and the mahcine fascinates her.... In my opinion LA ink is a good show with no swearing...it features strong, talented career women...no nudity or violence...I personally have no tattoos but appreciate them for their art....and I have explained o my child that tattoos are risky....sometimes they go wrong or you change your mind and its too late..anyway...so whichis worse? Are they both ok?