I don't think its about being scared of being racist, i beleive its the history behind it all.
It's like that programme i watched last week with Asher D from So solid: why is it ok for a black person to call another black person a nigger, but not a white person? Slave labour was banished years ago, and the one word which people remember is nigger...
Everybody is racist in a way, you may not notice it, but we all are.
But then when we talk about other peoples ethnicity.....ok what was everyones initial thoughts when the London bombings... I'll be honest, I made a racial remark, could be because of social views, but i generally dont hate other races.