I don't know how Social Security payout growth is determined in the USA, but in the UK, it used to grow inline with average earnings or RPI (whichever was higher), however, when Thatcher came into power, she pegged the growth at RPI as to remove the link between average earnings.
This paid off massively, as RPI has consistently been lower than average earnings increases ever since. As a result, the UK's unfunded public pension liability is predicted to be just 5% of GDP by 2050. Compared with 70% for Italy, 105% for France, and 110% for Germany.
According to Nial Ferguson, in the book "Colossus", cutting the growth rate of payments per beneficiary by half a percentage point per year (for Social Security) would shave $15 trillion off of the USA's ~$45 trillion unfunded liabilities.
