The cost of the Supplemental Nutrition Assistance Program (SNAP) has been decreasing year over year when adjusted for inflation since 2021. It was also decreasing when adjusted for inflation from 2013 to 2019.

The logic for food stamps does not really apply to other programs though. The amount of calories people need is constant, so supplying a given population with enough food to survive should be easier as time goes on. However for most things, we're not aiming for a fixed outcome but one that scales with GDP. For example medicine - providing people with 1970s levels of care would certainly be cheaper adjusted for inflation than it was in the 1970s, but providing access to modern medicine in modern hospitals performed by current doctors is substantially more expensive, and providing 2050 medicine will be more expensive still.