We all read about slicking up an action and "reworking" and action to assure perfect feeding, especially for DG rifles.
Most of the techniques I have read about have a few common items. Opening up or beveling the feed ramp, rail polishing, etc.
Why wouldn't the rifle makers incorporate many of those modifications. Seems to me that a few minor changes to CNC machining could easily be part of the manufacturing. The result would probably be no rework for many folks and much less rework for the folks wanting absolute perfection.

Quiet Please! We smiths need a reason for being!

I am probably more lucky than most here. I find the new rifles I buy will in almost all cases feed and function satisfactorily enough to hunt with even my 'Dangerous Game rifles'. I cannot remember ever buying a rifle that would not feed the most common of ammunition reliabily right out of the box. Now whether this rifle fed as smoothly as a well used Krag was rarely the case. The question is 'was it immediately usable for what I purchased it for'? On most of my rifles I may modify the follower to feed the last round more efficiently and maybe smooth up the feed ramp and railsbut I do this mostly because I have the necessary skills but more probably simply because I like to tinker. Most of my NEW bolt rifles have been large caliber Model 70's,CZ 550's and Rugers and I can't think of a single one I HAD to modify to make function properly. I really feel sorry for most on here who have such bad luck and feel somewhat guilty that I have such good luck. It has been this way for me for over 50 years,sadly.

DG rifles aside. I believe it is more of a feel that is desired then an actual function. Like Zim said will the rifle function out of the box?
It may not be as smooth as you desire but it will work and work fine.
Keep in mind we are talking good well built rifles. As soon as you get into the lower end stuff even name brand lower end stuff you may experience problems.
As for a simple program change to the manufacturing process. Well thats not everything that is done to smooth up an action and increase the reliability of it's feeding. There is a lot of hand work that can't be done on a cnc. Polishing is one of them. Honing the action is something a machine can't do with out some serious time devoted to the programing of the machine.
Then most rifles are built to a happy medium when it comes to followers and feed rails. Re cutting these to the particular cartridge it will feed would add to much time in production. making it cost prohibitive

From a practical standpoint, finding a production DG rifle that will function reliably 100% of the time is virtually impossible. That's been my experience, even with Custom Shop rifles from both Winchester and Remington as well as Dakota, Ruger and others. I have NEVER bought a DG rifle that did not need some degree of work to make it 100% reliable, and I have bought 7 over the years. The ONLY exception has been a Browning A-Bolt II in .375H&H, a caliber I do not consider acceptable for DG.

I am currently having a custom DG rifle built on a Winchester M70 WSM receiver by SSK in .458B&M caliber. I fully expect it to be 100% out of the box; hope I'm not disappointed.