I don't think you totally understand the point behind safety cases. To say that any system is safe is not the same as to say everyone should have it. The business case still needs to stack up.
For example, let's say my car doesn't have any seatbelts - we all know seatbelts improve safety, so I should install them in all 5 seats in my car. However I never ever have any passengers in my car, so it wouldn't be cost effective to install all 5, so I save a few hundred quid by just installing a drivers belt. (OK, I know there is certain UK legislation which would be breached, but it's just an illustration!).
We have to use our Business and Safety cases in conjunction, neither can stand without the other. Our industry is one of risk management, the ultimate safety argument would be to stop issuing clearances (think ash), but the business would fall and none of us would get our pensions!
As for the use of ATSAs - I used to do that job, and there was nothing more soul destroying than having my skills and knowledge being wasted on "eastbound - buff... westbound - blue" ad nauseum! Yeah, lets allow some of our ATSAs who want to go to go, and lets get real value and contribution out of the rest who want to be there.
Finally - What is all this crap about a level playing field? Are people actually suggesting that we turn off electronic coordinations, mode C and S and TLPD just because not everyone has it?
BD has hit the nail on the head, we need to change wee bits at a time, different units have different requirements, and there are a lot of hard working people both in the units and in narnia who are working hard to make sure those requirements are met!
Right rant over.