I liked the article, and really helps lay to rest the financial industry's boogeyman of excess spending in retirement.
With regards to the spending data: I would hope the housing cost in the late 60s - late 70s would be much lower (unless it's for retirement home as Basenji noted.) Otherwise, the data suggest that most people still have sizable mortgages at that age.
Also, if you're spending $20k a year ($1800/month) on food and beverages - wowza! We don't really watch our food spending, and have never managed to get even close to that amount in a month.