curious question as a canadian. when our prime minister makes a budget, it really is his fault. He runs parliament and executive functions. The budget in the USA is supposed to be a congressional matter so why does the president get any blame?

The Executive is the most visible branch of the US government and it lends itself to celebrity worship and cult of personality, being embodied in a single person. Most Americans can't name their representatives at any level but everyone knows who the President is.

And like a CEO, the President tends to get credit for everything.