Probably a mix of all of them. We should trying to convince clubs to sign young players on 5 year deals... that's one way to do it. A-league clubs rip up contracts all the time, then said player literally joins a rival on a free hahaha...which is crazy to me so that's one way to stop the duds.
A lot of trash agents too who are the brother/father or cousin of the player who maybe doesn't do the best job in getting the best fee... agents in Europe sometimes work specifically for the club to get a good deal.
500k for Bennie who has played some minutes in championship is insane... there wont be many 18 year old's getting game time in that league. Archie Gray went for 40m quid was it? surely Glory could of got ~2m for him.
TBH I'm not sure we ever will, the modern game requires supreme athleticism... our best athletes play AFL or NRL. That's just how it is unfortunately. NRL/AFL clubs are proactive in the search for youth they out there looking for these athletes(even if they play another sport), I don't think NPL/A-league clubs are... they just have a trial game and see who shows up.