Why wouldn’t Congress pass a federal law that prohibits discrimination against married people?

Most laws banning discrimination are “federal” laws, meaning they originated in the US Congress (statutory law) or federal courts (common law). Title VII, the ADEA, the PDA, etc., are all “federal” laws. But, federal laws don’t provide all the protections against discrimination that we enjoy today. Naturally, “state” law provides additional protections not covered by federal law. Research this topic and identify, in your own words, what additional protected classifications are covered by various state laws. Make sure to pay special attention to Nevada. In your paper, I want you to offer an explanation why federal law doesn’t cover all the protected classifications that exist. For example, why wouldn’t Congress pass a federal law that prohibits discrimination against married people? Some states do. Why are some protected classifications left to the states?