They can afford to demand competence, and they need it. But they don't always get it.
They are the reason it can be hard to hire qualified C++ programmers elsewhere. You compete for the rest who find Wall Street and monopolists both morally repugnant.
I would say programming is really difficult and it is hard to find competent(pick an arbitrary line in the sand) for any skill let alone programming. Pick a field, and the web is stuffed full of people with battle stories of cleaning up after other people. This is actually a point or two against C++ as the breadth of it is so large. The trick, as in any practice, is to find motivated people willing to learn that are not stubborn in their set ways.
They are the reason it can be hard to hire qualified C++ programmers elsewhere. You compete for the rest who find Wall Street and monopolists both morally repugnant.