I can think of multiple decade-long government projects off of the top of my head (including from NASA) that had entire programs scrapped because they ran out of money.
Overages from a single military program, like the F-35, have eclipsed the entire budget of those canceled projects.
You can't make actionable tweaks to the system when the books are compartmentalized.
None of that though doesn't cost money. Which is why I question the logic that Ad serving is somehow more responsive or accurate because a false-positive "costs money".
Ad companies don't get to hide their books from the public.
Many examples of the IC lying to Congress can be found with digging. Dirt can absolutely be dug up if Congress sees fit to do so. They just haven't seen fit to glex their oversight powers.