I imagine that at least most of the time it's possible to just drive a different route that takes more time.

Is it not?

It is, and this is what they will have to do. A lot of left hand turns in NYC - even in the outer skirts of the four major boroughs - cannot be made until the light has turned red, requiring a "New York/Pittsburgh Left".

They will have to route the car around in a manner that allows it turn from the right in that intersection.