Besides proxying to try to mask their activities, wouldn’t those playing host to bad actors have to have some insight or notice some abnormal activity that might give away that someone may be abusing their services?
Or is it that there’s a mix of a financial & legal advantage to remaining as ignorant to that activity as possible for as long as possible up till push comes to shove & they’re being served a warrant?
It’s pretty common for that sort of activity to use stuff like botnets or compromised servers. In other words, the actual owner isn’t aware of what their resources are being used for: they got hijacked. There’s lots of stuff on the internet with very lax security so unfortunately it’s not really hard to do.