People deny that they are discriminating others simply because they do not think that they are harming someone else. Perhaps, they think that it is justifiable. Or, because they are protecting themselves from some sort of harm, and they do not realize that someone feels discriminated due to their deeds.
If anyone could claim anything is discriminatory because they do not like their outcome of events, social and economic interaction would cease. It would be too dangerous to do business or even speak in the public domain for fear of being labeled something which may or may not be the case, with the resultant social stigma attached to them and possible legal consequences. Which is not to say discrimination does not exist or that nobody has been victimized, but if the alleged victim is allowed to self-designate a crime and then demand compensation with the full backing of the legal system without any due process what could possibly prevent abuse of that system? In the United States we have a right to a fair hearing and the right to present a defense in the legal system, but what is to prevent social stigma from making life unbearable for someone unjustly accused? Human nature will always find ways to abuse even programs designed to combat racism or sexism if they perceive a way to give themselves an advantage. There is no justifiable race or gender discrimination, but there are other reasons why people do not get jobs or do not make sports teams besides those two things. Merit seems to have been replaced by social engineering as a decisive factor in determining the best candidate for any kind of position, and as a result the positions suffer. Not because of the identity of the person but because of the ability. Which is not to conflate identity with ability, like the racist or sexist social engineers do by their belief that a person who is not like the majority in some way is incapable of achieving by their own effort without direct legislative action to make it impossible to fail. The removal of the possibility not to achieve is an insult to the abilities of the person or group they are allegedly trying to help. That is true racist or sexist discrimination.