Everyone who is awake discriminates – it is what people do with their minds, it's the way they know the world, more or less well. The kind of discrimination that's objectionable is when people use irrelevant attributes of others to classify them – like their race when hiring them for jobs where race is irrelevant. The race of a CPA has no bearing on the work of a CPA, so taking it into account in the hiring or promotion process is morally wrong, a kind of professional malpractice.
In a free country such discrimination may not be forbidden however offensive it is. No more than one may ban dirty talk or filthy movies or indeed any conduct that doesn't violate anyone's basic rights. (A legal right not to be discriminated against doesn't amount to the same thing. Legal rights can be granted by government, independently of anyone's basic natural rights, even opposed to them.)
In the US, however, some features of the civil rights law have made discrimination based on race, sex, national origin, etc., illegal for most people though by no means all. A clear case in point is that customers may indulge their racial and similar irrational prejudices with complete impunity.
If racists go shopping at the local mall, there is no law against their refusing to patronize stores where Jews, blacks, women or people with obvious ethnic backgrounds happen to work. Throughout the market place anti-discrimination laws actually discriminate mainly against sellers, vendors, proprietors, employers, and so forth. If a prospective employee stays away from places of work for prejudicial reasons, there is no law against this. If racists stay away from a restaurant because it is owned or employs people against whom they harbor racial prejudice, this is not legally forbidden. You will not be able to turn in such potential customers to the EPA and get any action taken against them.
It is probably quite impossible to force such customers to stop acting on their irrational prejudice but it is also quite clear that this amounts to the unequal application of the spirit and even letter of the civil rights laws that were enacted to prohibit prejudicial conduct throughout the American economy.
Perhaps this contains an important lesson. Conduct that does not violate others' rights may be very ill suited for governmental action. When people do violate the rights of others, this is usually evident by way of some actions that can be publicly observed – assault, battery, kidnapping, rape, murder, and so forth. But conduct that doesn't involve such violation is not available for control. This is akin to the problem with hate crimes – how can it be verified that someone commits a violent crime out of hate?
Of course there are some measures that can be taken to counter prejudice at a certain point of its manifestation. For example, if one opens up one's commercial establishment to all a sundry but then tries to inject criteria midway through the deal, when one notices that a potential customer is gay or black or from Bulgaria, that can be countered since the offer has already been made and to arbitrarily withdraw it can be legally actionable. Not unless the criteria, be these valid or not, are announced before the invitation has gone out to all a sundry to come and do business, may they be deployed.
Ok, but this of course has no impact on the great majority of market agents who are free to indulge their racism, sexism, ethnic prejudice and such by refusing to deal with merchants who may well have just the product or service, for the right price, they are in the market for. People who insist on using the government to make people behave well are facing a big problem with this.
But there is one avenue of recourse against the market agents who act irrationally, namely, to work very hard and vigilantly to educate them and to condemn them whenever their irrational discrimination comes to light. The trouble is that there has emerged such a heavy dependence on fixing moral failing by way of the law that such non-governmental approaches are not even explored, let alone practiced.