The US has a protection against double jeopardy. If you've been sued once for something, you cannot be sued again (and again, and again) for the same thing. In most cases this is a good thing. It means that once the case is done, it is really done.
But companies have learned how to take advantage of it. If they think they are going to have to fight a class action lawsuit that they are likely to lose, THE COMPANY will go to some lawyers, and say, "If you bring this lawsuit against us, we will cooperate fully, cave in quickly, and we'll settle on modest terms."
Said lawyers have every incentive to cooperate. It is easy money, and the more reliable they are about following through, the more of this kind of work they can get.
And companies have every incentive to do this. Because occasionally class action lawsuits happen that the company did not set up like this. That's when you get huge claims like the ones that took down big tobacco, or the hot coffee lawsuit that McDonalds faced a few years back.