But surely if there's a sign, you know damn well that you're being naughty by climbing it. That might be why you're climbing it, in part? What's at the heart of this isn't blissful ignorance, because if you've already been told, albeit by seeing a sign (as at Silbury) or having some inkling about what the Done Thing is (as at Stonehenge) then it's just willful not-giving-a-shit.
Is not giving a shit really an excuse to pat someone on the head and say 'ah it'll be alright when they're older and wiser! bless them!'
I think they should install some snipers round the base.