Lawyer cost - the ISP only does it when they get a notice, which is costing someone money. Studios have far more money to work wi… oh, wait, that’s right, studios are going bankrupt from the piracy, so I guess the lawyers for them are pro bono.
Added: some books might have some effort behind them. I would guess Harry Potter books were pursued to some extent, but even at their size it’s a small footprint to look for unless someone isn’t using any effort to conceal what the files are.
Detection - books are far smaller in size
Lawyer cost - the ISP only does it when they get a notice, which is costing someone money. Studios have far more money to work wi… oh, wait, that’s right, studios are going bankrupt from the piracy, so I guess the lawyers for them are pro bono.
Added: some books might have some effort behind them. I would guess Harry Potter books were pursued to some extent, but even at their size it’s a small footprint to look for unless someone isn’t using any effort to conceal what the files are.