"In my experience, the right wing is always asking 'What about me?' whereas the left wing asks 'What about them?' And that, in a nutshell, is why I will always lean to the left."
-Source unknown
EDIT: alternately, you could argue that the left simply has a more expansive definition of "in-group" than the right does, with fewer litmus tests as to who is granted membership. i.e. "I don't care about their skin color / sexual orientation / gender identity / disability status, they're still human beings and therefore we're on the same team." But it might be a distinction without a difference.