Confusing surprise

I sit down to pay my bills, and behold a letter informing me of my rights in a lawsuit I never even knew I was a part of.

AmEx is getting sued by a plantiff, whom I've never heard of. There is to be a settlement between the two parties. I have to go out of my way and write a separate "request for exclusion," if I want to be uninvolved.

I'm not in law school yet, but geeze, is it okay for a bunch of attorneys to represent an entire group of people without their expressed consent? It's obviously okay, since this letter I received was sent by the Order of the San Francisco Superior Court.

I tried to learn more about the case and discovered that the attorneys for the plantiff are big shot lawyers, who fight for employment rights, etc. Moreover, I learned that it's not easy to find background information on these lawyers.