I'm going to disagree. Modern manufacturing and automation has lent itself to very consistent production. Critical, no. But rather precise, yes (IMO). Making a socket hasn't changed
that much over the years, but within that realization comes the fact that Snap-On has many years of experience doing essentially the same thing. I'd be very surprised to learn that they produce anything near what a regular person would consider "inconsistent".
Also, I'm going to assume (perhaps to the degradation of my point entirely

) that SO orders proper stock for making their sockets. And by proper, I'm assuming it is 1) US made and 2) batch tested for consistency with regards to metallurgical composition. Now of course American made steel doesn't mean it's going to be consistent, but I believe it helps. Any manufacturer of tool steels, whether vacuum melted, etc. or not, tests their product all the time. They have to.
I'm also going to go ahead and believe (in my own mind

) that Snap-On regularly tests their production lines. I may be a bit biased on this point, every shop I've worked at was either a mechanical testing facility or a defense contractor that produced important (read: Government $) parts for reactors, jets, etc.