It's not just that the immigrant and minority communities served by shadow transit lack access to public transportation - those areas are also severely underserved by cabs.
I see this in action all the time, because I tend to bike late at night when bars are closing and people need cabs. If a cab does end up in Brooklyn, because they were required by law to take someone from Manhattan there, they tend to beeline it back to Manhattan, avoiding streets where they might encounter a fare. Smith St. / Clinton St. is one pair like this. Clinton St. is a residential street that leads to the Brooklyn Bridge. Nobody naturally wants a cab there[1]. Smith St. is one street over going the same direction, and it's all bars and restaurants. It also leads directly to the Brooklyn Bridge (actually, the Manhattan Bridge; they're very close). But you see most cabs opting for Clinton instead of Smith, so they don't get stuck picking up someone in Brooklyn that wants to go even deeper into Brooklyn. Instead, they try to get back to the highly-profitable Manhattan as quickly as possible, even if it means going empty.
That's not racism, that's just the reality of how you make money as a cab driver.
(The cabs that can't pick up passengers in Manhattan all take Smith St.)
[1] Except people like me that have noticed this pattern. I do see cabs stopping for fares on Clinton, since they have to if flagged down.
Do they abide by this rule 100%? How is it monitored or enforced?
hahahahah. They don't; not even close.
If you're already in the cab when you tell them then they're not likely to tell you to get out.
... under a bureaucratically-controlled pricing structure that ignores reality by forcing you to price all those routes the same.
Cab fares don't scale, so working the same time * lower fare = less wage.
I doubt they could afford to pay premium cab fare if they couldn't afford regular buses.
Cabs pull over, look at you, and drive off if you aren't the right skin color. It happens all the time.
They assume black people live in poor or dangerous or remote neighborhoods.
The law about cabs being required to stop is totally moot. Cabs simply don't pull over if they don't want to.
Go find a black guy and try to hail a cab with him for a few days. The data will really shock you.