The United States spends 2.4 times as much on the elderly as on children, measured on a per capita basis, with the ratio rising to 7 to 1 if looking just at the federal budget.
Second, most of the difference between spending between age groups is attributable to health care spending and pensions. Health care spending rises naturally with age, so that equally generous coverage will result in much larger spending on the old than on the young.
Viewed from a life-cycle perspective, it is not unfair to spend more on the elderly than on children because all individuals progress from being children to working-age adults to elderly adults.
Furthermore, the economic status of the elderly and of children differs little or not at all, based on poverty measures that take adequate account of out-of-pocket health care spending.