Why even have such a measure unless it's going to be at least $10/day as one likely needs at least that much just to feed themselves the cheapest possible food they can find.
That's enough for 50 servings, meaning you could feed yourself for $0.20 a day. Of course this ignores PPP, malnutrition and other factors, but don't underestimate how cheap food actually is.
All of the "staples" are insanely cheap - potatos, rice, etc. Most vegetables are as well. Toss in som emeat of whatever was on sale and you can easily cook a meal for 4 for 10 dollars, if not quite a bit cheaper.
http://www.heathernicholds.com/nutrition/frozen-vs-canned-ve...
At 200 calories per cup of cooked rice, you'd need 1.5 servings to get close to a "cheeseburger equivalent" meal in calories, and my "cheeseburger equivalent" system gives you 6-7 cheeseburgers per day at about 350 calories each. This means a person is eating 9-10 cups of rice per day.
That is a LOT of rice.
For example, in India $0.3 has about the same purchasing power as $1 in the US. US$1.9/day is thus about Rs 400/day in India, which is survivable. For example, a simple meal at a food stall will be under Rs 100.
Also, poverty definitions vary.
EDIT: 400 Rs/day = 12000 Rs/month which isn't horrible.
$1.9 doesn't afford you a comfortable life anywhere, but in the developing world, it's enough to not fear starvation. And that fear is a big part of being "extremely poor".
And I did not say this is the only problem with poverty.
http://blogs.worldbank.org/developmenttalk/international-pov...
PS You need to do the shopping, or learn to cook, $1.90 is very easy to feed people. But obviously it also about other things like food security and important stuff like happiness.
Out of touch much? While studying, I fed myself with about $10-15 a week, and I ate better quality food than most people. I live in a place where food is more expensive than the US.
You can buy the calories you need per day for individual cents, if you buy potatoes in bulk. Above that, buy basic ingredients in large quantities, and you will have plenty of money left for fresh greens to top off you meals. Don't eat meat in every meal, and meat should always be a flavoring, not what makes up most of the meal.
But the article is about extreme poverty. People who don't know if they're going to survive the next week or month. In the developing world, $1.90 per day provides just enough security that you're pretty sure you won't starve next week.
It's pretty damn bleak, but the fact is that a lot of people live in conditions where they know they may starve in the near future, and if fewer people live in those conditions, that's important.