The culture of extended childhood has gone too far. The reason kids are becoming mature so late is they have no responsibility and have not developed the ability to make decisions. I started working at 12, was mostly self-supporting by 15 and left home at 17.
My kids did not have the degree of hardship I did, but we homeschooled and I sent them to a local college between the ages of 14 and 15 depending on the maturity of the child. My daughter finished qualifications for high school a year early, and took a gap year between age 17 and 18, then enrolled in college on a scholarship as a transfer student because her school of choice cost more than her college fund. She will graduate a few months after she turns 21 and has her own apartment, and has lived on her own since age 18. My oldest was not launching fast enough, got booted out and is now a Marine living in Japan. The baby is serving a 2 year church mission in Norway and is 18.
Kids are given too much work and responsibility in the grade schools years and too little from middle school on. My kids had it easy little, but at age 12 the party was over. They each had jobs and the little one worked construction to help pay for his mission. When I say little one, he weighs 110 pounds at best and worked as a framer. He was working for a Marine who gave him no quarter and he learned to really man up. He was in serious pain the first few weeks and is a hard core martial artist so he is no wimp. Suddenly his desire to go to college has increased. I know it is controversial, but working a real job promotes an understanding of the outside world and real feedback. Employers don't care about self esteem.
The oldest told me having me as a mother made Marine boot camp easy. He said the little spoiled kiddies who had never heard they were messing up had a very hard time. Not that long ago 15 year olds were taking on adulthood. The reason the kids are not developing is because there is no need. It is like thinking people can get strong without some sweat and effort.