Players who don't use the forums (over 50% of law-breakers, I'd wager) won't recieve any warnings from the Admins, if such warnings are issued.
The admins don't want us informing players of the rules, and yet expect us to be their eyes and ears.
I dont like handing people into the cops who don't even realise they've done wrong.
It's subjective, really. I've seen you 'informing' others before and, to be honest, it hasn't looked as friendly as you would make out from my own personal perspective. For instance, you could be 'informing' someone, but, since you're not an admin with a firm grasp of the rules, you could be horribly wrong about your interpretation of the rules.
Myself, if I HAVE to inform someone, will do so privately, but generally I avoid doing so, since it invites trouble.
Of course, if someone mugged me on the street and didn't know they were wrong, I'd still call the cops, funnily enough.