I assume that you tongue is firmly in your cheek Oneye, as i'd rather go to prison for carrying a knife, than to go to prison knowing I had murdered a policeman, thus making someone a widow and some children fatherless. Dont you?
I don't carry a knife and I don't think that these feral kids have the luxury of thinking through their actions.
If a young male is carrying a knife as a weapon, then there is a good chance that he will use it.
If a policeman stops that youth, do you think in that split second, that the youth will be in a position to make a rational decision as to whether he should try and run; use the weapon or just say ' fair cop', that'll be me in prison then officer.