Do I think there's a basis for my forcing my views on them? Also no. I think it's difficult because you're looking at a change from the status quo. I'd suggest looking at it from a young upstart business perspective. If a new payment processor wants to start up that doesn't cater to the right -- or to the left -- should that be illegal? Probably not. Is it likely to happen and become successful? No, it's a terrible business decision.
> 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!