I know a lot of good, honest dealer techs and I also know some that I wouldn't trust to put air in my tires. For every bad dealer there are many more good and honest dealers. It is not unique to GM, all other manufacturers have the same problem. Some people are customer oriented others aren't.

 

I worked at a Ford dealer in 1980. Our "factory training" consisted of a guy from the Ford factory coming to the dealership and demonstrating how to dismantle and re-assemble some components on the bench. One guy was an accountant at the factory that they trained to do the presentation. While the dealer may charge $60 to $100 an hour, they likely pay the guy who actually does the work on your car $10 or less an hour.

 

Jennybeeb....if you go the new cap route, wait for a few tank fill'er ups before you declare victory . Back in the day of wrenchin' for a livin' the emissions evap leak test required that the vehicle be less than 3/4 full and be room temperture. For the lite to "set" there needed to be two cycles. Cycle being start, drive to operating temperture, stop cool down and repeat. It's a little more involved than that but that's the general ideal. In the mean time check around for a dealer/mechanic you can trust. Your orginal post sounds like you went to the one I got my SS from.