Lets also not forget that the Monk requires more XP because past 7th level they don't get to just level when they get the requisite XP, they have to defeat the current Monk of that level hand to hand with no weapons or magic items. Losing doesn't just drop the Monk back to the previous level, all XP above the minimum for that level are lost. So losing what should basically be a 50-50 fight costs a level worth of XP.Right, I forgot about that little discrepancy between PHB and DMG. Not that it helps the Monk a whole lot; the Cleric matrix is typically only 1 or 2 points better than the Thief matrix at the same levels.
I was looking at the higher levels, where Monks take 500K XP past level 12 to gain new levels, while the Paladin only takes 350K to do the same at that level.
Also, Paladins can qualify for the 10% XP boost with high enough stats. Monks never get that.
1st ed Monks from the PHB were terrible. There was a Dragon article which broke down how that version failed and presented anew version that was at least playable.