Perhaps you can argue this on a case by case basis, but do you think this is still true if you have to take or leave all service at once?
As evidence that the costs are worth the benefits I submit the fact that you (perhaps not you in particular but any citizen of a country who makes this claim) haven't renounced your citizenship for that of another, better cost-benefit ratio, country.
Incidentally, I think that if many government functions were privatized you would be paying a (much) higher rate than you are now since you've already shown the willingness to pay the current rate. That combined with the fact that there rarely if ever is competition in large scale services like those the government provides. As evidence, take a look at any large scale private contractor industry like construction or defense/aerospace.