No one ever expected them to approach US standards, but they have truly smashed even the most pessimistic expectations before the onset of hostilities.
No amount of battle experience can teach you a will to fight, and the Saudi military just seem to lack that.
Comparing them to the PLA during the Korean War is an insult to the PLA, and there are vastly conflicting casualty estimates for the PLA during the Korean War, even amongst western estimates.
If you insist on using the Korean War as a comparison, the Saudis should instead take on the role of the US, who enjoyed overwhelming superiority in weapons tech, yet still found themselves outfought by an opponent with only basic weaponry, but who had more recent battle experience and a stronger will to win.