@kagan One version of that is the observation by the police that some young men can be a right bloody nuisance from the ages of about 16 to 26 after which they settle down and become at least tolerably well behaved citizens.
"So, at the first sign of trouble, how's about we lock them up and release them at age 26 when their brains have matured?"
No, that won't work, say the police. Because what turns these lads into decent citizens is that they get involved with a woman who says "sort yourself out or I'm off", and there's no opportunity to meet such a woman in prison.