How so? Google is a major distributor of most pirated material through YouTube and their search engine still makes finding stuff easy. I'd argue that p2p is nearly irrelevant nowadays and server-oriented distribution is the main model.
At that point, I had gotten really good at spotting counterfeits, so I really doubt we were selling any counterfeits, especially when they couldn't come up with a single instance. The publishing companies continue to do this because used books cut into their profits.
I just sent my lawyer after them and they never came back.
Amazon and the publishers eventually came to an agreement that there were certain textbooks they just won't allow to be sold as used on their platform.
My wife asked me last week to help her get a textbook in a format that could be viewed on a reMarkable tablet, which can read PDFs but won't work with arbitrary DRM schemes. I checked my options and found the publisher selling some DRM crap, and some clearly illegal sites selling DRM-free PDFs. Since I found plenty of people vouching that they'd received what they bought, I chose to (using a Privacy card number) willingly buy from the criminals, since they were the only ones willing to provide me what I needed: an unencrypted PDF that we can actually use on the device we want.
I know publishers are afraid someone will email the PDF to the whole class, so that's why college textbooks probably ought to be folded into tuition, that way (1) publishers can get paid for the correct number of copies and (2) someone who actually has to pay the money (the school) is somewhat in the loop on textbook selection. It's broken now since those actually paying (students) have no say in book selection.
More likely because those people remain naïve about the real world. In a past career I had some interaction with IP enforcement lawyers. They were stuck in the past then and have not really evolved. Their understanding of "the internet" extends only to those things discoverable via google search. Megaupload was knocked down because it was so visible. Piracy is more alive now than ever, but as it is no longer visible via Google, the likes of the MPAA and IRAA cannot see it.