Now, I haven’t read too much into this, just skimmed over a few articles and watched a tv show, Mr. Robot, which had to do with illegal trade online and the topic really interested me in how they are able to be kept anonymous while still getting the merchandise. The most well known and popular black market I read about online was Silk Road (no longer in service) in which was created for users to have anonymity amongst the users for their protection. This meant that it could not be hosted on the public domain of the internet, thus meaning it would not appear on search engines such as google, bing, or duckduckgo.
The only way you could access “Silk Road” would be by using the dark web in which utilized Tor hidden service, so that the traffic could not be monitored by anyone for the protection of the users. An interesting fact I found was the the actual creators of Tor was the US government during the mid 1990s which originally was designed to protect US intelligence communications online. However, the only way for the government to allow this creation was to not only create it for specific people, which would allow the location of who created tor and what is on it which wouldn’t hide anything online, would be to allow everyone to utilize tor, thus essentially allowing illegal abuse of Tor to be allowed.
Tor network has had 4 million users as of 2013, thus allowing users to browse the web anonymously to stop, stalkers, abusers, advertisers, etc. as well. I also find it very interesting on how people think that taking tor down would solve issues regarding illegal activity online. It definitely will not stop any criminals from their intentions because they already have better options besides TOR. Tor is only used for illegal use by a minute set of people, and Tor already has a hole in which people can still technically be found through holes in the network. So it is not the safest for criminal activities to be fully anonymous. So it was better to just keep the network Tor up for everyone to use, including ‘normal’ people and the government.