blah blah blah ...
The trick is to ride, drive,run,walk ski,skate at your own ability.
YOUR brain,use it for YOURself.
The problem is that at sixteen, most have a vastly over-rated view as to their ability on a motorcycle.
At eighteen they know everything there is to know about everything.
The other thing is that if you buy a new bike and crash it, the manufacturers won't have resale competition.
Some unscrupulous ones may see this as an incentive to sell more powerful bikes which are more likely to be crashed. We've all heard stories of people who crash leaving the dealer lot.
That's also one of the reasons that the training programs aren't as difficult as they could or should be, since they're sponsored by said manufacturers, who want more people on bikes. The trainers do try to cram as much knowledge into those thick heads as they can though, so kudos to them.