How do you do cash payments over the internet? Thats the whole point, enabling illegal commerce over the internet.

If I were to put my game theory hat on, I’d take it one step further and say “crypto is good for crime” is a meme likely promoted by gov institutions.

They get a criminal financial system committed to a permanent public ledger. Between deanonymization techniques and zero-days, its likely they view chains as an asset. They can use them to see how money is moving through criminal organizations. Best of all, it’s likely they never have to reveal their hand (they are using chains for investigations) since they can use parallel construction once they know where to look.

Except that you are now committing your crime in a single jurisdiction and performing all elements of the crime at the same time. It makes it much more convenient for law enforcement to catch and prosecute you.

And what's worse they have incentive to get you to roll on your dealer. So they're more likely to hammer you with charges to force you to take a deal to testify.

Compare that with my situation. You need to prove that I received the package, associate that shipment to an order, that order to a payment, and that payment to me. It's a multi-jurisdictional effort that would require subpoenas and some sloppiness by my dealer.

And to what end? All I know is that I sent bitcoin to an address and drugs showed up some time later. I have no idea who I paid, where they got the drugs, who mailed the package or anything useful at all.

All the other comments here seem to be speaking strictly of illegal drugs that otherwise can't be obtained. There is also a market for things like semaglutide, HGH, any sort of anabolic steroid, ED drugs, certain types of stimulants and asthma meds, that are fairly trivial for any American to get a prescription for from an online clinic in the next half hour if they want, but they'll be charged extortionary prices. You can also buy these same things for 1/100th the price from well-established, well-known black market labs that will reimburse you for third-party blind purity testing, and nobody is ever going to arrest you for it, public ledger or not.

Or take your chances handing over cash to some dude in an alley.

Monero or XMR is supposed to be untraceable and is now used by a lot of DNM's

If you're concerned that bullet-proof math might not stay bullet proof forever you want want to just shut down your computer right now.

My FedEx driver is a drug dealer and he don't even know it.

(1) Install tor

(2) Search reddit/internet for marketplace on tor

(3) Be very sure that you have actually reached the marketplace. Lots of scammers MITM them and steal your crypto by changing the pay to wallet

(4) Buy crypto (which kind depends on merchant & market place)

(5) Place order on marketplace

(6) Send crypto to the address they give you

(7) Encrypt your shipping info with the merchants public key and send it to them

(8) Drugs show up 1-2 weeks later