Main reason being this: Most schools teach basic nutrition, i.e that eating less/more food than you need, can/will result in losing/gaining weight. In this day and age, it is common knowledge that eating junk and being sedentary will cause obesity. And even if there are groups of people that don't know this, obesity has hit all socioeconomic classes - not only poor people.
Likewise, I don't think that if we suddenly teach everyone financial literacy, we're suddenly going to poverty plummeting. I don't think poor people are poor because they don't know how to pay their bills on time, invest in index funds, or that having a maxed out 35% credit card will make your debt outgrow a 8% savings fund.
I think poor people are poor because they're trapped in low-wage jobs, and are often forced to use more expensive services, as well as being victims to centralization and ever-growing rents.
edit: With that said, I think basic financial knowledge should be school curriculum - but I don't think it's going to be the magic bullet.