Actually, the younger you fuck up, the worse are the consequences. A 13 year old go in a school fight, he is kicked out of school, has to go in another school further away, sleep less, see his grade fall down, and next year he'll be pushed to start an apprenticeship rather than high school.
A 31 one year old (otherwise a good citizen) does the same. He'll spend a night in police custody and at worst pays a fine (with a high probability that change are dropped because judges and prosecutor are busy)
That's a very unusual example. If you're prepubescent you can get away with straight up murder in a lot of jurisdictions and basically go back to your life after a few years, of lots of therapy, and legal supervision.