As I understand it, many if not most states allow prosecutors to remand anyone older than nine or ten but under 18 to be tried and charged as an adult in adult courts and then sent to adult prison. The ages vary by state but in most of those states once you are remanded as an adult, no matter the crime you are legally considered an adult subject to adult penalties from then on. .This circumvents juvenile/ family court protections and denies youngsters and their families the benefits of therapy and intervention tailored toward juveniles. It ignores the fact that kids make mistakes and since sex is what most young kids are most curious about many kids are going to make sexual mistakes and if given the chance and not thrown into the adult system, most of them will mature, gain impulse control and make better decisions as their frontal cortex matures around 25. (some people have even married and divorced a 'sexual mistake' before age 25) but a lot has changed since the AWA went into effect and today (I think I read somewhere) there is a surge of names of young people labeled "sex offenders" whose names are being put on the S.O. Registry whose crime was committed before they turned 18 (let alone 25) but who were adjudicated / remanded into the adult system. As you said, .tried as an adult but not (yet) legally or emotionally adults.
There's a well researched book, put out by Human Rights Watch titled Raised on the Registry if you are interested in finding out more..

Politicians used the slogan "Adult time for adult crimes" and the citizens cheered.

Yup - none of us understand it either. Or at least I never have - in cases of sexting the underage person sending photos of themselves is the victim AND the sex offender and they often receive adult size sentences

Something that concerns me is that "pedophile" / "Budding Pedophile" is the new buzz word, new label haters now use to telegraph ( Bad seed... "Once a monster always a monster" in place of the less PC labels like Pervert, Baby-raper you name and they' want to punish it

Setting aside the fact that no matter who or what age person anyone may be erotically attracted to just being "attracted" is not a crime. (even old Jimmy Carter said he lusted in his heart!) But no matter what the primary attraction might be whether or not the attraction is enacted depends on who the person is as a whole, Age, Self control, Maturity, Past traumas, Ethical values and so on are the crucial/ the deciding factors (look don't touch is a phrase preventing many mature, ethical adults from straying into forbidden territory ...whether the "attraction" is a daughter who looks too much like her mother at the age when he met her mother, or a sweet little kid or a next door neighbor's wife or the paper boy,,, ) The difference between acting out and attraction depends upon t=who the entire person is or might become as he (or she) chooses not to act upon their attraction and betray their own "better selves."

I believe this is doubly import when considering young kids not only because their values, their better selves, and their impulse control is not yet fully formed but because .kids who "offend" offend with other kids. Once they are charged they are labeled child molester, child predator, because as Advocate says kids experiment / have 'sex' or sext or "inappropriately touch" other kids (if kids have sex with some actual adult then the adult is assumed to be the "Child predator")
But once a child is charged as an adult in adult court they too are labeled "Child predator" "child molester", "Child -Porn addict" from then on every time the kid is "Evaluated" the labels affixed make him worse. The pre-sentence evaporators use words like " Child Molester" in the psi The media says Child Pornographer,/ Child sex offender (after all he molests children doesn't he?") as the labels progress the "offender gets more dangerous Dangerous baby-raper until the new buzz word "Budding Pedophile" gets applied and then outright Pedophile is the label affixed ...

Words Matter, labels and evaluations morph as the haters and Prosecutors and "Protectors of Children" know far too well. A scary label applied in adult court is as good as a "Win" no matter the age of the "child" or the reality of the entire person "evaluated"

And not to belabor the point the label Pedophile is affixed as though every adult person erotically attracted to child was a wild man a predator with no self control, no better-self not an entire human person but a monster entirely defined by the evaluaters and the haters and the media by the words and the prejudice attached to the labels used by predatory prosecutors to win convictions