Don't get me wrong, I agree with what you say in principal but when you've got people living out of food banks and 40% of America's homeless despite being in full time employment (I don't know the UK figures), principles go out the window, so i wouldn't be so quick to judge.
FWIW, I'm fortunate enough to be able to afford the choice and choose along more ethical lines. I'd also encourage others in a similar financial position to do the same but understand not everyone can.