I don't understand what is missing from "the left's" response to aging populations. The left's idea, as I understand it, is to encourage fairness of opportunity, which I assume would be both between members of one generation and also between generations.

Over time, as the population distribution shifts, the revenue from taxation of the working population may go up or down, and the community must decide what level of taxation and what age of retirement is required to provide adequate support for those unable to work. You can do the calculation at a given point in time or you can try to do some sort of smoothing over time.

The right's idea, as I understand it, is to move towards social Darwinism, with the aged, infirm, young, and otherwise dispossessed to be instructed to take their problems off to a place where they aren't so noticeable.

What is the question?