the point with apprenticeship is, it asures a high level of quality as not everyone can get in. It's a form of secondary eduation and the selection process by employers simply ensures a high level of reliability (i'm idealizing, here) also, it's not uncommon for a 40 years old to take a new, shortened apprenticeship, before changing jobs. the effects you see reversed are in fact not hierarchical but in a feedback-loop, education is but a factor.