Immaturity is not a juvenile crime

Should five teenagers, who dropped rocks from an overpass until one killed a random motorist, be tried as adults? The inconceavably thoughtless act was murder, sure, or aggravated premeditated manslaughter for certain, but was it the crime of an adult? It was not. I’ll concede that immaturity can be criminal as an adult, it should be impeachable for adult presidents, but not for juveniles. What is the point of differentiating juveniles from grown ups if you’re going prosecute bored stone throwers as adults?