Except that I KNEW all of them were either instructors, or master certified technicians, or both, and I have no idea at all about who you are or what your credentials are, so it's kind of hard to attach value to you "being the first". And I mean absolutely no offense by that at all.
As far as the vendors are concerned, I've seen light to moderately warped condition out of the box for rotors sold by Brakes best, Duralast, Carquest, Napa, Wagner, ACDelco, Centric (A lot of them, from this company), Raybestos, Durago, Beck Arnley, Bendix and others. So that tells me that the majority of them are probably coming off the exact same Chinese assembly lines, which, for the record, I disagree that they DO manage to peddle rotors that are straight and true or if they do they are certainly not remaining that way while traveling on the containerships.
In fact, hundreds of times I've received boxes with, for example, a Brakes Best product decal slapped on the box over the top of what is obviously a Wagner or Centric or other product brand label. Same product. I'm saying that's ALWAYS the case, because we know it isn't, but it's the case OFTEN.
The only rotors I've never found any issues with (And that's probably because I haven't used them very frequently because of cost, are Bosch, Power stop and Brembo.
Still, it's just my opinion and I thought I'd offer it here as contrast to the bad vibe on brake lathes. One thing I fully disagree with as well that was this comment though.
I have to add though, its race products so the rotors are fairly costly to start off with, which makes the financial decision easier
On race vehicles, IMO the rotors get replaced, every time, not turned, ever, because taking off material on these rotors is a very bad idea. They are going to heat up faster if you turn them down from being thinner, they are going to warp MUCH easier BECAUSE they heat up faster and further and they are going to be unsafe because they are almost certainly going to promote fade.
Race vehicles and very heavy duty trucks and suburbans, etc., are scenarios where I'd always replace if there was even a question of just breaking the glaze not being good enough.