In theory democratic government is the check on this - if the government wastes too much money, the electorate is supposed to vote out their representatives and elect new ones that will cut the budget. (In this sense, Reagan-style conservatism is working as intended). In practice, this rarely happens, largely because the average voter is terrible about judging opportunity cost, and every expenditure seems worthwhile in a vacuum.
This is a bit like saying that the goal of government is GDP per capita. Yes, both are important, and both are indicators of doing a good job at something, but what a business does is the most important thing: how does it adapt to reality and make sure it is always doing something useful enough to pay for?
Government doesn't necessarily do things people want to pay for, as then it might do much less stuff, but people do want to feel as though they're getting value for money from their taxes, and that the government isn't spending so much that taxes go up vastly and their currency is inflated so much their careful savings are wiped out.
All of this is to say is that even though large corporations and large governments are alike, the most efficient solution for a corporation (bankruptcy) is not a good solution for government and so despite the inefficiencies we are sort of forced to accept them as the engineering realities of the situation. I fully understand large governments have large government problems, I just don't agree with the notion that having a smaller government is a solution and that the small government meme has largely been toxic to the detriment of the middle class.