IME – living with a girl who worked in the House of Lords and was very politically correct, she felt she was doing 'right' by sticking up for minorities who couldn't stick up for themselves. In principle it made sense, but in practice she seemed to be assuming that other people a) needed and b) wanted her to stick up for them. Which is actually quite patronising. 'You're black, society discriminates against you, therefore I will stick my nose in and help you, whether you want it or not' She was white middle class.
She was also a control freak and there were certain things you weren't allowed to believe if she deemed it incorrect. Like when I suggested a girl should go to Brownies if she couldn't go to the local Cub Scout group….!