I think the answer to the OPs question is that aviation regulation isn't always very forward thinking, regulatory changes often are made only after an event has occurred. Over here, we have yet to see a fatal incident involving a low-hour F/O who has paid for the training themselves.
That said, one would think that the Kos incident back in 2006 would have really given the regulators something to think about. Incidentally none of the three safety recommendations from the AAIB report into the Kos incident concerned pilot selection, despite the fact the F/O had failed simulator assessments which formed the selection process for his training. Despite my only flying being in the world of gliding, it seems to me that the key problem here of pilot selection based on ability to pay as opposed to ability to fly was missed.