[1] DEFINITION: The age at which a person is no longer excluded from criminal liability. The lowest age is indicated for countries where there isn’t a single age limit, for example where different states have different regulations (such as the USA) or there is different limits for boy and girls (such as in Iran). The spectrum is specifically wide for the USA and Mexico (both 6-12 years). Several US states do not stipulate any minimal age for criminal responsibility at all.
[1] https://www.momjunction.com/articles/gift-ideas-for-6-year-o...
Editing since I can't reply: I may have misread your reply to mine, I reacted because in my mind, that there's a range or discretion is irrelevant because it's so far out there in the first place. Cleaned it up to be less pointed, to better line up with my intent and hopefully yours.
You should really look at the numbers. The rape rate in the US is 17X Canada. Murders 3X. And the US age of criminal responsibility is SIX?! [2] It's pretty clear whatever system you advocate for isn't working.
[1] https://www.macleans.ca/news/canada/7-charts-that-tell-the-s...
[2] http://www.nationmaster.com/country-info/compare/Canada/Unit...