Why are we not teaching our young children about sexual abuse, instead of just dealing with the aftermath?

Why are we not teaching our young children about sexual abuse, instead of just dealing with the aftermath? http://www.internetsafety101.org/pornography101.htm

I know that child abuse will never stop..it will only ever prevail and escalate, especially via the internet. What I cannot get my head round..is we teach our children about all the usual dangers in life, but not about one of the most dangerous..that of paedophiles and sexual abuse!! Research states that one in four children will experience different levels of sexual abuse, I think that it's possibly more. Yet we warn them plenty about 'dangerous roads' or 'dangerous dogs' etc..I think that it's because sexual abuse is so taboo and people prefer not to talk about it, it's far too unpalatable to even think about. And it could marr their child's innocence. I have heard parents say, "the school want my seven year old to receive sex education lessons, I think that is way too young!"
What they probably don't know is that more and more children now, have seen hard core pornography before they receive sex education! I know of 5/6 year olds who have seen the worst, most violent porn, including bestiality!! And of course, children are being groomed and abused on all community sites, there is even hard core child porn on facebook!

Times have changed..There is no longer innocence in this pornified and sexualised society of ours.

So would it not be better to teach children about the 'real world' in the likelihood that a paedophile will take their innocence and marr the child with psychological damage for the remainder of their lives??