* Your role is an employee is to help accomplish a corporation's objectives.
* (In this case) the corporation's objectives are unethical.
* You're contributing to something unethical.
That being said, nobody is perfectly ethical. But if I worked for Amazon or PayPal, I'd have quit by now, and I'd never have taken a job with MasterCard in the first place.
I also don't mean "held responsible" in a legal sense, either. They've done nothing wrong legally. Legality != morality, though.
But they are responsible for those they know about.
Most people don't have the option of just up and quitting their jobs.
Even if finding a new job is easy, it's still difficult. I just went through this process, it's still rough...
As I said, everyone makes choices. Everyone commits minor works of evil. If doing wrong is worth your mortgage... it's your life.