Let’s say that the cantons, several of them from every political perspective, actually get control of their federal taxes, and are able to direct how they are spent. Congress continues to make laws and allocate expenditures, but always with the foreknowledge of which cantons can be depended on for which expenditures, when it comes time to cough up the dough.
Let’s further say that the current expenditure before the Congress and the cantons has to do with an undeclared war somewhere in the world. Certain cantons have stated that they are willing to contribute to the funding of any conflict that the current Commander-in-Chief declares to be necessary. Other cantons have stated that they will contribute only to wars declared by Congress, or none at all. Will this situation cause the war to be under-funded? Not necessarily. Those cantons that are willing to pay for the war may have more funds to contribute to this cause because they are not paying for some other government programs, thereby making up for any shortfall caused by other cantons not contributing. Likewise, those cantons not willing to pay for the war will thereby have additional funds to contribute to government programs they alone favor.
And what about those government programs no canton wants to fund? Or what about those cantons unwilling to fund any government programs? These situations could be considered a natural form of “stimulus” spending, since these funds would go directly back into the productive economy, creating jobs.
Thus, every person, thru their canton, pays only for those things they believe in, and to the extent they find palatable. This provides the means to finally “right-size” government.