It's their prerogative. The cab drivers take a loss too. as long as they aren't leaving people somewhere dangerous in the middle of nowhere.
You and several others have made this point. However, I don't think you're right. Taxis have a license to transport people and are, in effect, common carriers. This typically obliges them to accept any passenger to any destination within their licensed area unless the passenger appears to be disorderly or dangerous. Taxi drivers who refuse to take passengers to a rough part of town or pick up women (on the suspicion they're bad tippers) are rightly subject to discipline and punishment. If the driver does not want to accept the legal and ethical responsibilities, s/he should find another line of work and not victimize law-abiding persons in need of transportation.
"It's their prerogative. The cab drivers take a loss too. as long as they aren't leaving people somewhere dangerous in the middle of nowhere."
Sorry, it's not. They operate cabs pursuant to certificates or licenses that impose "common carrier" obligations on them, one of which is to serve all customers without discrimination.