Inertia's definitely important but 75 years is a long time, long enough to discount it as a valid excuse. But if we're allowed to dig into history a contra example is another ~70 year old system, the UK's NHS. That system managed to pull itself up by its bootstraps in spite of the loss of empire, material shortages, and left over war ruins, and a superficially more discouraging class system than our's that turns out to have more upward mobility than our system. Weird.