“For example, in 1929 people spent 20% of their income on food for home use. Today that number is only 5.7%.”
Remove welfare and food stamps back to the 1929 level and recalculate that and see what you get.
You ask and you shall receive. Food expenditures as a percentage of money income excl gov't assistance: 1929: 19.3% and 2012 11.4%.