They get charged as adults in court all the time. Girls of this age can get pregnant and in some places this makes them a legal adult regardless of age. Most places in the US they can get married. It's hard to feel they are full children given all this.
Also, they can't get treatment without parental consent, which is not true of most of the above.
Edit: and I forgot join the military! Statistically far more people regret their military service than their gender care.
I was gonna say this was some high-quality bullshit but after this year I just assume RFK Jr. was involved somehow.