I would point out, however, that this aspect:
"...Unfortunately there is also the occasional ODA that creates a situation that reflects badly on the rest of us."
is not restricted to just the A Teams (sorry, I'm old ) -- echelons well above that on the SF side can get in the Supreme Jerk mode occasionally. It's rare but regrettably, it's not unknown.

With the right training and support, any good infantry unit can learn to sneak and kick in doors at oh-dark-thirty; that's been demonstrated. Maybe not as good as those that specialize but good enough for most work. SF brings another real strength to the table that the best Infantry unit cannot do well. Kicking doors is a whole lot more fun but, as you said, the real winner is the tedious, hard, dirty, bad food work with the locals and that is one thing the Army, per se, will never get good at doing. Nor, probably, should it do so...

Back to ODB's original question; what I hear is that since Iraq has so much more 'big army' and a covey of Generals it is more tightly structured and there are more operational constraints -- and jealousies -- whereas those working in the 'Stan have a freer hand and the distribution of forces and the type and location of bad guys enhance that. That plus a lack of a pervasive host nation governmental presence sticking their nose into everything...

I suspect the recent change of higher Hq in the 'Stan may have an adverse impact on that; we'll see.