I wouldn't rag on this too much, it's a good idea.
100 savings out of 2000 income is much better than most (only a 5% savings, but on a low income lower savings is expected), and that $25/day is supposed to cover all food costs and all other spending (like starbucks, clothes, etc.) besides a $100/mo
"other." The rent is cheaper ($600/mo).
It's actually decently reasonable, IMO. Could they cut down? Sure (the cell phone is $100/mo, for example), but this isn't as bad of advice as some of the personal finance sites out there give.