I’ve read short papers from unis several years ago pointing out that there was absolutely nothing stopping the feds adding more nodes; or compromising them in various ways. Many of the European ones are run by intelligent young men with good careers; often the cops don’t want to completely fuck up their lives as that is a surefire way for them to get into even more serious crime; nor are they going to shut down hosting companies that often also supply servers for legitimate businesses. I expect most middle class young lads today who who end up sat in cell for just a few hours; having had thousands of Euros of computer equipment seized and possibly fearing being judged for helping spread kinderporno or terrorist material are likely to accept a deal where cops leave them alone and even let them have the computers back provided they keep themselves out of trouble.
It is also easy for casual TOR users to misuse the software in such ways (often unintentionally) that it makes the whole network less anonymous. At particular risk are those in student houses using the DOCSIS cable networks (which are heavily monitored for commercial reasons and whose owners also have big contracts with cops/feds/public authorities) or the halls of residence where the uni provide the broadband.
In many of the papers it was clear that the profs had been monitoring their own unis networks to search out TOR use and were able to identify the physical locations where this occured in the network without needing to decrypt the data (which kept this within ethics guidelines).
The harsh facts are to understand crypto properly and use it safely you need to be good at maths and computer science and willing to put the effort into going through lots of code; whereas the drugs culture is based around hedonism and instant gratification.
TBH I think the use of these services for selling drugs is only a short term solution anyway (and can add to other problems in society) when what the world really needs is a society where the only encryption needed is the same stuff to stop your card details being misused, same as buying a computer or anything else online.
