I know they don't care about it. That's the point. They don't care about it but they do it, because it's socially expected that they do it, because it's mainstream. If being green was counterculture, greenwashing would have the opposite of the intended effect.
As a corporation why would you co-opt something that the public in general isn't on board for? Ask several people on the street "Should companies be more green?" and they will mostly say yes, as that is a mainstream idea. If you wanted to be counter culture you could start a company that isn't green, "We pollute ten times what our competition does!", lots of people out in the culture would be very upset, they would protest, that's what being counter to the culture is like.
And you think weapon manufacturers are sincerely concerned about discrimination and human rights in general?
Mainstream culture has been co-opting countercultures since decades. There are even words like https://en.wikipedia.org/wiki/Pinkwashing_(LGBT) and https://en.wikipedia.org/wiki/Greenwashing.
Music genres like punk, rock, rap etc have been watered down in the same way. And many other things.
That's the opposite of going mainstream.