It's the insurance companies that dictate the experience levels. If it costs the charter company $20,000 a year to have cover for all their 1000-hr-plus pilots but it costs $50,000 a year to have newbies, which way do you think they will go?
But in Oz we let newbies fly the simple stuff, and don't let them near an instructor rating until they have 400 hours. Or at least it used to be that, but the new Grade 3 starts them sooner, can't say yet if that is a good idea or not.