Well, you don't have to assume that 100% of all violations of laws will be caught to get a stable society. Just that enough of them are caught to deter most potential criminals.

That's a tradeoff vs. the benefit to a criminal who isn't caught from the crime. The benefit here could be enormous.

it should be pretty obvious if someone suddenly makes a dozen illegal copies of themselves and suddenly starts using far more network resources then they were a short time ago.

I was assuming that creating illegal copies lets you use the same resources more intelligently, and profit more for them. Also, if your only measurable is the amount of resource use and not the exact kind of use (because you don't have radical transparency), then people could acquire resources first and convert them to illegal use later.

Network resources are externally visible, but the exact code you're running internally isn't. You can purchase resources first and illegally repurpose them later, etc.