What explains this? To put the answers simply: Politicians like big government; voters like big government….
Politicians do indeed like big government, for the same reason that prostitutes like big sales conventions. We all benefit from high and growing demand for our services.
But it’s an all-too-common mistake to infer that whatever government does in a democratic society is what “the people” – or even what “the voters” – want or like. A number of well-known public-choice reasons support the conclusion that what government often (typically?) does has only little connection with the genuine wishes of citizens or voters. See Arrow’s Impossibility Theorem, along with the work (among many others) of Anthony Downs, Jim Buchanan, Gordon Tullock, and George Stigler.
The illicit move that the modern mind makes when it encounters the concept of democracy is the following: When people vote, they choose; therefore, the results of fair, majoritarian elections reflect the wishes of the people – in the same way that the results of my strolling into a department store and choosing to buy a pair of black leather shoes reflects my wish to own such shoes. The only difference is that elections reveal and implement the wishes of ‘the people’ as a whole, while my choices in a department store reveal and implement my wishes as an individual.
Ask: if you saw me sleep-walk into a shoe store to buy shoes, would you conclude that, having purchased a pair of shoes, that I really want these shoes?
The fact is, the vast majority of what government does is not known by the typical voter. Voters’ actions in some ways enable government to do all that it does, but mostly what government does remains unknown to almost all voters. Therefore, how is it possible to claim that voters want or “like” big government if most of what big government does is unknown to most voters?
A different take is to recognize that democratic voting is a tragedy of the commons. Even if every voter is adequately informed, the institutional free-for-all that is politics means that fully informed voters who might genuinely prefer smaller government nevertheless vote for representatives who bring home the pork because these voters believe that voters in other districts will elect pork-barrelers to office. Voters, in this scenario, no more want or like big, pork-slinging government than do livestock owners who graze their animals on open-access pastures want or like the pasture to be denuded.