Yes i understand what your saying, and i should have covered that in my original post, but yes your right, organisations like the RSPCC are valuable, and parents cant just go around hitting their kids willy nilly, without reason. If thats done then there is no justification for violence, and the kid will ultimately turn to violence without the need to justify it.
But then again the procedures and everything that is in place holds the parent down from doing anything physical after verbal warnings, iv heard it so many times where a parent has gone to discipline their kid, the smallest slap, the kid calls the social and they get involved and by the time you can say help, the kid realises he has made the biggest mistake of his life and is in a foster home getting adopted by people he doesnt even know.
But i agree with your second statement, parents a certain minority of parents say are lazy, are too preoccupied, and are just not ready to be parents.