I once a took a completely stock Monte Carlo to a dealer with an intermitant no start problem. I even offered to let them use the GM shop manuals I had for the car. The response was "We have all the manuals - we don't need yours." The next day they return the car saying they can't find the problem and that will be $200. Needless to say they didn't get paid for their good intentions. The really sad things is that I used the manual that they turned down, followed the diagnostic chart (the very one the Dealership Techs Must followed) and solved the problem.
I really think the problem lies with the way these techs are paid.
if the book pays 2 hours for a repair and it takes him 6 hours guess how much the tech gets paid... yeah 2 hours.
Now I'm paid hourly. and I could care less if it takes me 8 hours to find the problem, if it's justified (tough electrical short) then so be it.
at the end of the day it's fixed
There is not much incentive to fix your car if he's not getting paid.