People who sell online are very different from those who sell in-person. Most come from socio-economic backgrounds where all kinds of anti-social behaviour is normalized. They are also not "professional" so to speak, and do not know the words Op and Sec. Someone who's selling acid on the net will not rob you, since they're not dumb enough to. So it's an apples to oranges comparison in my opinion.
Regardless, I do wish they would cut it out with the useless arrests. Good job, you seized a car-full of drugs and some dudes who mail drugs, do they think the global drug market has felt real hit? That unlike at every point in human history in which something was prohibited, the black market will just stop? That this actually puts a dent into the bottom-line of criminals? Even if it did, momentary weakness by one criminal group is an immediate invitation for another to expand.