As I understand it, each Broadway cab driver is an independent contractor. As such, he alone is responsible for his or her actions. I'll agree that Broadway should have responder better, but they already paid a fine for that. Broadway has no control over the actions of the cab drivers, so I don't see how they can be held accountable for their actions. Why wasn't the second driver held responsible also?

The driver was fined because he didn't respond to the investigators, NOT because an investigation concluded that he kicked them out because they were gay.