Because the firearms industry, like the NA auto industry was able to write it's own ticket for decades, and willfully ignored foreign production methods. The NA gun makers have been forced by the market itself to recognize that there are other makers doing it for cheaper, and with a quality that will meet NA standards. Quite frankly, like the auto industry, many of today's value guns are still miles ahead of what was offered a few decades ago.
The introduction of value priced rifles from the likes of Savage, Remington, etc shows that they learned their lessons. If you can't beat 'em, join 'em.
The quality of these rifles is quite good. In comparison to some of the other higher priced / quality rifles, they aren't quite as nice for "feel" this is true. But it does allow a new hunter, to get into the game, with a budget in mind. I see a few posters have commented on buying a quality "used" gun, instead. Great strategy, it's how I got into the sport years ago, but buying used also means that you could be buying someone elses problem as well ( gee, why do you think they traded in that nice little rifle in the 1st place? It's not always because they just got tired of it).
I own a very nice CIL .308 ( made by Parker Hale) bought used. love the feel of the gun, and it shoots nicely. I also recently bought a Savage Axis in .308 in stainless. I have to admit I didn't like the action on the Rem 770, but I did quite like the way the Axis felt. For the money it was a decent buy for Moose hunting in NFLD, and it shoots quite nice. It also cost less with taxes, than my CIL did, even used.
The proliferation of decently made, "value" guns is here to stay. you can buy your Benelli semi, or you can go buy a Stoeger M3500 which has the same action in it. Fit and finish isn't quite the same, but clay birds will break, ducks will fall, and turkeys will sound their last gobble just the same. Weatherby has it's scatterguns made in Turkey by Armsan, they are quite nice. I have a Mossy 20G semi built by the same place. I have a Winchester 1500 XTR which is 30 years old, and great quality, but IMO, it's no better than some of the "value" shotguns like the SA-08 out there today.