“Though I’m sure I’ll get flamed for this, but frankly, it doesn’t sound to me like the cab driver was being particularly unreasonable. He called the guy another cab—what, this guy can’t wait five minutes for another cab to come around the corner?”
Yes, you should be flamed for this. By your logic, I can discriminate against anyone based solely on the premise that the next person they meet will not discriminate. If you went to the store and they stopped you at the door and told you to go to the store across the street, I think you would be upset. If you tried to buy a ticket to fly to another city and you were turned away and told to take a bus I’m sure you would be angry.
As I've noted before, this isn't precisely accurate. The cab driver didn't discriminate against the person, his actions were directed at the dog.
If you tried to buy a ticket to fly to another city and you were turned away. . .
Happens kind of a lot. They put you on the next flight and life goes on. Sort of like how this guy would have gotten in the next cab.
Besides that, as someone else noted, these cab drivers are typically independent business folk. If they want to refuse service to some people, I don't have a problem with that.