Because Snap-on and Stahlwille blow everyone else away in terms of precision. You can verify this with a micrometer.
Odd, because every measurement I've ever taken tends to see most hand tools come out to be identical the the thousandths of an inch. Usually the only difference is when I start looking at the ten-thousandths of an inch. They are a few exceptions that are a few thousandths off from each other, but all of those tools have worked well and I can only assume that a difference of a few thousandths is more than acceptable, seeing as the fastener is much more likely to vary a higher degree than the tool.
Now, granted, I haven't bothered to measure the 60 sockets for $4 type tools, but Snap On, SK, Proto, Craftsman, Gearwrench, Tekton, Pittsburgh pro all have come out near identical in my measurements. I'd be more comfortable saying that the difference between sockets of different brands is near immeasurable and any differences found are more likely due to measure error than they are to differences in the specs that the sockets are manufactured to.
Mass production of products accurate to the thousandths is no longer a difficult task. In some areas outside of hand tools, we are already mass producing things with tolerance ranges being only a few nanometers or less (and that is being done in Taiwan interestingly enough).
10x is quite the claim. I'd love to see the data behind that
As you already suspect, he has no actual evidence. It's like the people on this forum that say "insert brand name" is so much better than "other brand name" because they can feel how much "tighter" the socket engages. There is no part of our body that can tell the difference of tens of thousandths between two items.
Hand tools are very low tech. They aren't difficult to manufacturer.
Good job team.