Can't help but wonder
Technically, it is perfectly feasible to restrict profile viewing of adults to only other adult profiles. If that was done, then said 24-year old could simply not have sent a message to pseudo 13-year old since he would not have seen the "girl's" profile.
And if, for the sake of argument, one had to admit that sometimes adults should be able to view underage profiles, it could be restricted to requiring that the younger one initiate contact first, by sending a request to that effect. One could also imagine that parents could have automatic access to their offspring's profile for parental control.
If this measure was implemented, the only real issues we would have is with the real pedophiles posing as underage teens and trying to catch a new victim. Prosecution would be easy, because there is no way an adult can pretend that he didn't realize that he was creating an underage profile. Once caught, he'd be hooked for good.
So now, if this is technically feasible and not all that difficult to implement, why isn't it done ?