Penny wise and pound foolish

Why are people such financial retards?
They can't handle wasting +20% price on vegetables but easily rack up late fees. And they don't listen to me.

I'd say that what most humans want first and foremost is to be well-fed.

Its obvious food is central(all organisms require food/energy), and denying that energy trigger survival instincts.
http://www.inquisitr.com/135667/any-society-is-three-square-meals-away-from-anarchy-suggests-researchers/