You asked for examples, someone got you 4 examples 5 minutes after you asked, and you immediately discard that as 'not enough examples'. That doesn't bode well for any kind of rational discussion.
To answer your last sentence: Lets' rephrase (again) it to this and see if it rings some bells:
" So, if only 1.% of the developers are negroid ... but fewer than 0.1% of comments on development mailing lists are racist ... what is the real "problem" that exists? "
Imagine that rather than having a naked chick every so many slides (as happened in a talk @ GoCaRuCo), you would have a picture of a negroid in chains animation pulling in the next slide of the presentation. Add a whip to the scene and it would make even a mostly white audience severely uncomfortable.
I think we're just far more sensitive to racism than to sexism, which makes it a bit harder to pick up acts of sexism.