I also find it odd that disc weights need to be hand written on - cant they automate that?
I think you overestimate the sizes of these companies. It's not like they're big corporations with giant, state of the art manufacturing facilities.
I've seen the newer Ching discs with little stickers on them giving a time stamp and the weight down to a thenth of a gram, but I don't really see the advantage. I don't see much flight difference between a couple of grams, anyway. I think pepole make a lot bigger deal out of that than is warranted.
As for getting discs consisant from run to run, I'd guess that that's not finantially possible for the disc companies. Injection molding to tight tolerances it touchy at best. They'd need environmentally controlled chambers with extra cooling time and robotics controlling the injection molding machines and I don't see any of the companies (or perhaps even all of them combined) selling discs fast enough to make that possible. I doubt any of us are willing to spend $40/disc until they hit their ROI on all that equipment.
One thing I will give you is that retooling molds and keeping the same name has gotten out of hand. It might have "flown" in the past, but I'm afraid to buy a disc that's been out for less than a few years becaues I don't know what I'm going to get. Am I getting the Teerex, Teerex-X, retooled Teerex, the retooled Teerex-X-L special edition with kung fu grip or what? If I throw an Eagle, it could be an Eagle-X or L depending on the plastic and year it was made, but no matter what it's called the Eagle and there are, IMO, major and important differences in how they fly. I liked the Beast before they retooled it. After they did that they should have changed the name because it's clearly a different disc. The Speed Demon by Gateway is just as bad. Apparently there have been nearly 10 retoolings of that one mold. It's gone from the most overstable disc ever to basically the same as the straightest Spirit. What about the Buzzz? There's the first run, second first run, midnight (which are apparently similar to the second first run) and then normal runs. How many "Rocs" are there? Even if you don't include the Classic Roc there are three distinct molds out there that are called the "Roc." I understand that they're trying to give customers what they ask for, but when you already have a process that isn't horribly repeatable it makes it difficult to choose discs when they add in even more variaion.