[...] you claim that this is common to all Arab armies. I wonder whether it could be explained by any situation that combines high power distance and mass poverty.
I think it may also have to do with the (nomadic) tribalism origins in the entire region which linger on in M-E politics today. If you're 'naturally' distrusting of (individuals from) other tribes and their political goals / ambitions on a bigger level, that may also work on a lower cognitive level. You may want to keep them away from things (like knowledge, information and connections) that may threaten you and your clan in the long run.
I also think the machismo culture has a lot to do with it as well. If you've been treated as a 'little prince' at home (and probably quite 'we Arabs/Turks/etc. are awesome and always right'), you may (over)stimulate the Dunning-Kruger effect and loss of face becomes a psychological treshold. The Dunning-Kruger effect is where one
due to lack of experience and knowledge, thinks one already is an expert, knowing everything there is to know already and is therefore above critique and reproach. Thus making one less receptive and open to training, tips and taking orders.
Play any online game and you'll find thousands of such people who would rather throw a tantrum or do the most foolish things or making bad decisions like saving oneself rather than holding the line and work for the group.
The Dunning-Kruger effect is also known to stimulate scapegoating and throwing tantrums, but usualy has the effect of either someone ending up panicking and making bad decisions, due to lacking discipline and training and disintegrating as an army, or to simply give up while blaming everything else, rather than try and work harder.
Being told by foreigners that you need training therefore probably isn't very effective until they fully realise and admit to themselves it's true and even then don't have any other options than to admit they were wrong to an external party due to the loss of face (and standing) involved with a public admittance.