Earlier quoted context omitted.
When there's a big power imbalance, putting the onus on the service provider to give a valid reason for denying customers can be more impactful than laying the burden on a user to prove there was discrimination. Depending on your race/ethnicity/disability/socioeconomic status, taxi drivers might refuse service even though it is against the law. It is easier to win against a taxi driver if they're obligated to explain…
I respectfully disagree because that goes against individual freedom. I understand that historically in the US there's been racism but that's no reason to erode individual freedom.
Now, I would agree with you if we were talking about individuals. In that case, yeah, I think you should be able to refuse service for any reason or no reason at all to whoever you want. But if you go and get a corporate charter from the government that, for legal and fiscal purposes, creates an entity that is distinct from you-the-actual-person, then I don't see any problem with the same government telling that distinct entity what it can and cannot do. That entity has no natural rights.