As a PADI instructor, and one who has taken several NAUI classes, I find this thread funny and tragic at the same time. Funny, in that "the usual suspects" make the same snide comments they usually make concerning that "other" agency -- tragic in that "the usual suspects" make the same snide comments....
I'll admit I'm not at all sure WHY PADI won't allow an otherwise qualified person (DM, AI, Dive Con, Instructor, etc.) be a "Certified Assistant" to a PADI instructor during any PADI class. The one rationale I've heard, and honestly may have some validity, is that PADI has a pretty strict set of standards as to what a CA may, and may not, do while not under the "direct supervision" of the instructor. I have no idea what a NAUI CA may do while supervising students independently of the instructor so I'm willing to cut PADI slack here. (Perhaps we can all imagine that plaintiff's attorney questioning the NAUI DM -- "You mean to tell me you didn't know you weren't allowed to take poor Jane's mask off during her first Open Water dive that led to her terribly painful hangnail?")
So, assuming THAT is the reason, then it seems to me that PADI should allow a "cross-over" after completing the Standards session of an IDC or DM class. But that's just me.
Regarding the "requirement" that PADI staff "sell things" -- well, not really -- and even if it were true, so what? I hope ALL people involved with instruction encourage students to get more involved with diving -- buy their own gear (one thing we know is that a person is much more likely to dive if they have their own gear); go diving (another thing we know is that people who don't dive -- well, DON'T dive and their skills atrophy); take trips, whether local or not; continue learning and improving. None of these things are bad and if we, the people who are involved with the education system, don't encourage our students to dive, who will?
There is NOTHING WRONG with selling the right thing to the right person. Or, as was true in my former direct marketing life, it is only "junk mail" if it isn't something you want or need.