Government agencies seldom have any incentive to be thrifty. Rather, they tend to misspend as much money as they think they can get away with, blame poor performace on a lack of funding, then mis-spend a large part of any additional funding they get.
While it would be an oversimplification to say that the amount of money actually spent for good and proper purposes is independent of taxes raised, tax increases seldom produce a commensurate increase in proper spending. Rather, tax increases provide the opportunity for government agencies to eke out more money for their own purposes.
Government needs to be kept 'hungry'. A government which is not fiscally constrained will not only abuse its citizens' pocketbooks, but it's likely to use the money to harass citizens in other ways. The only way to keep government 'honest' is to ensure that it can't afford to abuse its citizens.