I think I see where Rickys confusion might lie.
One can buy a corner weight checker for quick track use - it costs about £150, and simply lifts each wheel in turn a fraction and checks the effort to do it. Because of the way it works, simply adding the 4 results up may not give an accurate total vehicle weight. Just knowing the relative proportions between wheels can be enough sometimes for a quick check.
Using electronic 4 wheel scales though, (as they do at SVA, and as Tony did) does both at once, and accurately.
I would have thought that someone with as broad a reach of knowledge as Ricky usually claims might have known that, though.
