Every individual is biased and discriminates in some way as you wrote in the post. But this causes not too much problems as long as each individual discriminates in a different way, so that everybody may be discriminated by some but favoured by someone else.
It becomes more problematic if the discrimination is orchestrated and coordinated, for example by an ideology, so that substantial parts of the population discriminate against the same group of people. This is what anti-discrimination measures usually target and try to break up.