Terry Doe campaigned for years and years to have a standard test introduced, he was as convinced as you are Ray about how easy it should be and how much benefit it would have to the peace of mind of airgunners.
But... a few years back he stopped campaigning after the complications from a political and practical point of view were explained to him. He's now of the opinion that a standard test would be a bad thing for shooters.
I can't remember all the details of why that would be, I just remember his conclusion was that after receiving expert legal opinion on the matter it's better for us as a whole if we don't have a standard test.
That's good enough for me.
Why don't you give Terry a call and get him to explain it to you? - let me know and I'll PM you his number.