Its apparent - and real - neutrality makes its judgements and recommendations a commandment not to be avoided and, almost universally, to be obeyed. The CBO operates for and on behalf of the American Congress and is, really, the research arm of that venerable parliament. Parallelly, the executive part of the American system - the Administration - has its own guard against waste and worse: the Office of Management and Budget (OMB).
Both bodies produce learned, thickset, analyses, reports, criticism, opinions and recommendations. Despite quite a prodigious annual output of verbiage - they are so highly regarded, that virtually anything that they say (or write) is minutely analysed and implemented to the last letter with an air of awe.
Only a few other parliaments have committees that carry such weight. The Israeli Knesset have the extremely powerful Finance Committee which is in charge of all matters financial, from appropriations to procurement.
Another parliament renowned for its tight scrutiny is the French Parliament - though it retains very few real powers.
But not all countries chose the option of legislative supervision. Some of them relegated parts or all of these functions to the executive arm.
In Japan, the Ministry of Finance still scrutinizes (and has to authorize) the smallest expense, using an army of clerks. These clerks became so powerful that they have the theoretical potential to secure and extort benefits stemming from the very position that they hold. Many of them suspiciously join companies and organizations which they supervised or to which they awarded contracts - immediately after they leave their previous, government, positions. The Ministry of Finance is subject to a major reform in the reform-bent government of Prime Minister Hashimoto. The Japanese establishment finally realized that too much supervision, control, auditing and prosecution powers might be a Pyrrhic victory: it might encourage corruption - rather than discourage it.
Britain opted to keep the discretion to use public funds and the clout that comes with it in the hands of the political level. This is a lot like the relationship between the butter and the cat left to guard it. Still, this idiosyncratic British arrangement works surprisingly well.
All public procurement and expenditure items are approved by the EDX Committee of the British Cabinet (=inner, influential, circle of government) which is headed by the Ministry of Finance. Even this did not prove enough to restrain the appetites of Ministers, especially as quid pro quo deals quickly developed. So, now the word is that the new Labour Prime Minister will chair it- enabling him to exert his personal authority on matters of public money.
Britain, under the previous, Tory, government also pioneered an interesting and controversial incentive system for its public servants as top government officials are euphemistically called there. They receive, added to their salaries, a portion of the savings that they effect in their departmental budgets. This means that they get a small fraction of the end of the fiscal year difference between their budget allowances and what they actually spent. This is very useful in certain segments of government activity - but could prove very problematic in others. Imagine health officials saving on medicines, or others saving on road maintenance or educational consumables. This, naturally, will not do.
Needless to say that no country officially approves of the payment of bribes or commission to officials in charge of public spending, however remote the connection is between the payment and the actions.