Agree on the transparency, but I think the whole blockchain thing is a bit misguided. A blockchain is neither necessary nor sufficient for transparency.

Much would be confidential, classified, blacked out, etc ..

But that aside, you going to go through $7 trillion of payments each year and revenue? Billions and billions of transactions annually likely.

There is a reason the Treasury dept is so big, nevermind the millions of other employees who spend money.