> Should a business be allowed to refuse service to someone because they are black, for example?
Is it distasteful? Yeah. Is it a good business model? Nope. Should they be forced to do something they don't want to do? It's hard to say. Discriminatory behavior shouldn't happen, and where it creates material harm (employment, for instance) recourse must exist. Otherwise, I don't know, where no harm occurs it's difficult to justify forcing action.
> Does your answer change depending of whether that business has many competitors (e.g. a cake shop) or is a near-total monopoly (e.g. google)?
I'd suggest when something becomes essential and doesn't have competition then it becomes "de facto infrastructure" and open access rules are justified.
I'm trying to come to a conclusion myself here. Thanks for making me think this through!