Okay Mr. Canadian, I'll try my best to explain it. The first thing you have to remember is that food stamps are a recent invention compared to the history of the country. Not that recent, but they came around just about when the boomers (for some of us, our parents. For others, grandparents) were about to be born.
So, when the framers got together to design the Constitution, food stamps did not exist (they weren't even an idea of the time) and they were deathly afraid of a powerful government (a mix between the circumstances leading up to the Boston tea party and the slavery question/compromise between the North and South). So, under that framing, the founders were dead set on having the power of the purse being under as many people's representation as possible. That is why the power of the purse and the allocation, of which the allocation of food stamps would fall under, is in Article 1 (Congressional powers) of our Constitution.
Yeah it can't get its shit together but, at the same time, with the jackass we have now, putting the food stamps (or any allocation of the budgetary allotments) under the control of someone so petty is actually a godsend.
I don't know what fail safes Canada has, so I can't speak to that. However, does our Constitution need some amendments? YES As to what those are/would be, I cannot say because the list is too long. I think one of the reasons we are having such issue now is because our political system has been so captured since Regan that half the country feels like its living with a crazy lady in the attic, and they don't want to feed the insanity any more than necessary. Is that a bad way to keep a country going? Probably