There are certainly cases where an employer intentionally discriminates based on some kind of animus: racism, sexism, bias against a particular religion, etc. But there are also case where employers discriminate without any such intent. Alas, the discrimination is just as illegal. Take customer preference, as an example. A customer or client tells an employer they do not want
Can the employer legally honor the customer request? No. Period.
I recently delivered discrimination training to a group of (mostly male) executives. One asked a great question: his wife does not want him traveling with other women on business. Is it ok if he only brings male employees on business trips? I hope you can guess the answer (no!). Simply put, spousal preference is not a legitimate reason to discriminate. The fact that the executive bears no ill will towards female employees is of no consequence. By honoring his wife’s preference, he would be denying women advancement opportunities. And that would be just as illegal as refusing advancement opportunities to women based on his belief that they are inferior.