So the author completely botched what "50-30-20" means. 50% is supposed to go to fixed costs. Rent, Utilities, Car payments, Healthcare (other issues with including this raw cost in Take Home Pay as a majority of people have the majority of this covered by employers). 30% is day to day spending: Groceries, Gas and probably that "Other Necessities" piece would be included in this. And then lastly 20% to savings. This would include all savings. Savings for future cars, house down payments, etc. would all be included in this.
What this results in is the author double counting money all over the place, so these numbers are all needlessly inflated because the author is a moron just trying to get pageviews.