The core question is how much of what most governments produce are "public goods" and how much is "social engineering" or "bureaucratic busywork"? From what I have seen most of what the government provides today is "social engineering" or "bureaucratic busywork", and even the "public goods" they do actually deliver tend to be full of "social engineering" and "bureaucratic busywork" ...

Privatization (often) eliminates these wasteful and pointless activities, but it is not (necessarily) the only way to do so. If there was the political will to do so, you could probably achieve similar results while keeping services publicly delivered; but this would require significant reform to the electoral system to prevent gains from being erased the second someone else came to power.

The most important public goods that the government provides are defense, justics, and transportation.  Its not a perfect system, but its the only system that works, and without the government providing them we simply would not have them. 

Can you imagine our entire transportation infrastructure being dirt roads?  That is the best the private market would provide us, as only the government can provide such a public good.  We would literally go back to the Dark Ages, which was the last time Western civilization moved away from government in favor of privitization.

Being that many cities and states/provinces already contract a large portion of the construction and maintenance of transportation infrastructure to private companies without any negative consequences, why would contracting out the production and maintenance of road infrastructure lead to humans devolving to the dark ages?

I'm not clear about your argument.

Taxation is the only way to provide funding for roads.  Currently, Transportation Departments and City Governments decide what roads need to be built or maintained and what they can afford, then they either design the project in house or contract a design agency to design the project, then they bid the project and reward it to the lowest bidder In most cases its the lowest bidder anyway, the two states that I'm familiar with have a law requiring the lowest bidder to win the project and the other has a reward system where contractors who aren't the lowest bidder can still win the project if they are within a small percentage of the lowest bid and they fulfil more 'desired parameters' than the lowest bidder, such as being in state, mandatory random drug testing, non-discriminatory policies, etc.

It must be strongly noted that there are definite differences between a public-private partnership and purely private enterprise. Take roads for example, a public-private partnership involves the government (at whatever level) contracting out road building and maintenance. Purely private involves the roads being built and maintained by private companies and being paid for through road tolls.

Public-private partnerships are (in my opinion) a good idea for a lot of things that do not strongly risk human lives, such as transport infrastructure, communications infrastructure and maintenance of public areas.They probably should be generally kept away from things like fire service, ambulance service, prisons and defence though.

Just a note: private companies, in my experience, do a great job at EMS when needed. I worked dispatch for our local police station, and we contracted EMS when the city had all crews out. I also worked at said EMS company after leaving dispatch, and they did a fantastic job. So I think the line can be blurred betwen what works through private entities, and what must strictly be public. Don't get me wrong, matters of justice are probably best suited to the government, but I think that is about the only think that really needs to go in the government column.

While I wouldn't recommend it with the current state of laws within the United States, the judicial system could (theoretically) be privately run. When you think about it, all the judiciary is supposed to do is make judgements based on the legal framework that has been created by the legislative branch of the government, or precedence set by a higher court, so as long as the legislative branch and supreme court are managed in the best interests of citizens lower courts could be privatized. Unfortunately, when you have multi-thousand page laws  full of contradictory and poorly written rules it is unlikely that a private business would be able to consistently judge cases.