Barry, I believe everything you say, but it does fly in the face of what I was taught. A couple of things don't add up.
First off, why do all the major manufactures still have etch primer as the base for their life time warranties (at least the last time I looked)? They are putting HUNDREDS of MILLIONS of dollars on those warranties. They do the same salt tests, why in the world would they do that?
I used to have OEM requirements for repairs on their vehicles to maintain the OEM warranties. I don't remember all of them, but many had a requirement of etch primers. Getting your paint system oked by the auto manufacture is no easy task as you may have found out. They REALLY test and retest these products (or do they just study the paint manufactures test results?) and getting a product on there is not easy. In fact, most products on the list were the previous generation or older!
How are these products salt spray tested? Did they have protection over them? In other words where the primers top coated with a urethane SS or something like that? Where the etches top coated with a urethane primer and then urethane SS or similar?
What about etch under the epoxy, how does that stack up?