Okay, but isn't median household income something like $52k per year, which would generate about $2400 per month in social security payments?
If so, then the family with $52k per year, pre tax today, would receive $29,000 per year in retirement funding. Given marginal tax rate differences, that may only drop their money for expenses by $18k. If they now have a paid off home, medicare, that is a fairly small drop in monthly living costs after retirement.
So the people with an additional $25k or $50k saved up for a vacation, a car, of medical expenses are doing ok. I noted that the survey was of currently working folks, and many only start saving in their final 5-10 years, (e.g., at age 50, with kids moved out and maybe the house paid off) which can easily accumulate that amount.