I'd say the biggest spur to leaving the nest is not money or a desire for independence, but the opportunity for anytime sex in your own pad. WFM.
I go to graduate school and travel 40 miles home 3 weekends a month. Dorm apartment: crappy electric oven/range, no fridge space, too much traffic, crappy thermostat. Home: great gas oven/stove, free food (mwahaha), less traffic despite being in NYC borough, nice & cold temperatures for better sleep! In all seriousness, a lot of my peers really are still living at home for various reasons. My fiance is saving tons of money by staying at home and as soon as we're married, it's off with me she goes. A lot of people really are moochers though. It's like HS/college/careers insufficiently train young adults to live on their own these days...
High School really doesn't do much for you... there are plently of career *planning* things, but none actually help you write up a resume or give a list of local job openings. Also driver's ed. is separate from schools now, so students have to arrange for their own way to learn and pay for it, so driving is less common, which means harder to get jobs that you can actually get to... It all just gives you great goals, but no means to achieve them
Well, realistically, I know that HS doesn't usually do squat for life preparation, but I didn't want to ignore that one can be successful even without college "preparation". For a select few, HS is enough preparation. For others, no amount of school is sufficient. It's sad to say, but there are so many so called college-educated folk who don't even think to check the date on a milk container and cannot operate a room in a shared apartment, let alone operate independently.
I won't be moving back with my parents after graduation, well not for long anyway. It's a completely different lifestyle without parents not just the Sex thing, but no moaning, parties whenever you want, no need to ask permission for people to come over/do stuff. Yes there are bills etc.. but the benefits far outweigh the cons.
I had a Co-OP class in high school where I worked the second half of the day, once a week the Co-OP students met for the class and thats what we did. We had to do all that stuff that teaches you how to live independently. I still live at home because school is a 20 minute drive, work is close enough and it lets me save money to spend on more school. The free food is just a bonus and as soon as i get my degree I am out of here.