It’s not even that clear-cut. When it’s a matter of responsibility, the left sets the agenda that “they’re just kids”. When it’s a matter of abortion, sex, etc, the left sets the agenda that they’re old enough to decide without parental “interference” (though the local leftist makes sure to insert their agenda, propaganda, what-have-you into the process).
Such as trying vicious murderers as “children”, even when they’re 17 and outweigh most adults, and helping them seek abortions without telling their parents, but punishing them if they bring an aspirin to school.
The left doesn’t care about being consistent, logical, or using common sense, they do whatever pushes their agenda, even when what they support one day completely contradicts what they supported the day before.
I agree with everything you said....