If you're looking for the actual basis for this, that would be the Civil Rights Act of 1964 and the Americans with Disabilities Act, and all of the numerous way

If you're looking for the actual basis for this, that would be the Civil Rights Act of 1964 and the Americans with Disabilities Act, and all of the numerous ways in which these doctrines are required to permeate how the executive branch protects citizens against many forms of discrimination. The US has sweeping anti-discrimination laws, and they apply to private business too. This shouldn't be a surprise to anyone who has learned about US history.