It's all about the green, about the green, no yellow...

If you think about it, the Flash's powers wouldn't help him catch a cab, although he could beat it to where he wanted to go.

And if Green Arrow shot one with an arrow, he'd need to use another trick arrow to jack up the car while he changed the tire.

Of course, the probability of Batman catching a cab in the rain is 100%, metaphysical certitude, because, you know, he's Batman.