"Guns don't mass murder people, humans do"
In the real world, if I saw a child go on dates with a grown adult, I'd alert the police and have the man arrested, then I'd do my damndest to have the restaurant shut down for facilitating the grooming of minors.
And most importantly, _in the real world_, we all have visibility of this and society as a whole acts in disgust and would (legal or otherwise) punish the offenders and people who facilitated and accommodated this.
> There could be a set of rules that the apps should make users agree with
A pinky promise maybe...