Varies from person to person. No one is perfect after all. There are many factors that go into who is and isn't investigated: Obviously rich kids who skip out almost can't ever escape without their parents bitching, assuming they're aware of the situation in the first place. High level characters tend to also get priority if only because their assumed good records are something that Purple Crown wants to maintain. Kings and guild leaders are also obviously monitored. Now just some random level 1 student who got bored of Deep Ground? He'll likely slip past the system and never really get called on it. He goes maybe about 3 or maybe 6 months and he'll find his Deep Ground Account suspended. Goes for a year and it's deleted. And no one would have told him a thing, unless someone actually cares about such thing.
And yeah, there's on-the-job training. Plenty of packaging and shipping companies can and will teach you how to load and unload boxes at the most optimal rate for 6 hours straight. If you're hoping to get some sort of on-the-job training for a lucrative or at least respectable career, you're outta luck. If you can't even play a video game through highschool, why would any business think you'll do any better with an actual job, which is likely going to be just as much of a monotonous grind? Just without as much social interaction.
Your standing in Deep Ground is essentially your college degree: every job needs one now, and by no means does having one actually mean you're better than anyone else. Just that you've had the time and money to spend for it, which makes you a better investment then the ones who try to go without.