https://www.quora.com/profile/Eric-Pudalov  asked me to answer this question.  He gets me fired up on questions like this, one that has an absurd premise based on false assumptions. 

First let me rant a bit on various Quora questions where the phrase "dark web/deep web" is in the question. I guess I need to take a class on new age grammar where you can use a slash to join phrases you believe to be synonyms. I added a link at the end of this question to help you sort out the definitions of deep web versus dark web.

So that gets me to the second part of the rant, dark web and deep web are not synonyms. Just like "deep web/black market" shouldn't be joined together like this, they are not synonyms.

Assuming you mean to say that the dark web is synonmous with black markets, and you are asking why doesn’t the government shut down the dark web, let me address that question.

The dark web is a complex communication system that exists to allow anonymous traffic. Many people make the assumption that all anonymous traffic is related to illegal activities. That's not exactly true.  People living outside the U.S. don't always share our freedoms, like free speech. Dark nets are used to get information into and out of places where free speech can get you killed.

Are you suggesting we block all dark web access? There are many people using the dark web for reasons other than illegal activities.

Taking the question one step deeper, let's discuss why doesn't "the government" shut down black markets. They do. As the link in this question shows, one of the first dark net black markets, Silk Road, was indeed shut down by the FBI and Europol.  There are many law enforcement agencies working on shutting down black markets, but many illegal activities originate in countries where "the government" has no jurisdiction, or has no cooperation from the local governments. 

What would be the plan for the government to "take down" the dark web?

In some cases the countries where black markets exist are the same countries where people are using the dark web to get the word out about their governments. What would you suggest, we isolate the entire country from the internet? 

Knowledge is power

Learn how to travel the highway safely, whether we are talking motor vehicles or web browsers. Knowing where you are going before you stumble blindly into a new place will help keep you safe. That's up to you, don't always expect the government to protect you from your own stupidity.

The dark web is one segment of the internet, and like the internet itself, you will find good things there, as well as evil.

Don't be afraid of the dark, in this case, the dark web.