The potential loss of porn producers is far, far greater than that of video game, music or film producers, yet they ***** about it the least, in fact, not only do they not ***** about it, they also don't commit to only producing 'safe' products with minimal investment the same way as the other industries do (seriously, you wouldn't believe how much technology gets adopted because of the porn industry).
Ultimately, it's because porn producers are forced to live in the real world. There is no government support which makes it hard to litigate things, there are not really internationally famous porn stars complaining about piracy and, above all of that, it's a fiercely competitive industry so there's no room for DRM and the other poor decisons other companies make. They are forced to act in an economically sensible way, and complaining about or wasting time trying to recover sunk costs is not economically viable.
Ultimately, it's because porn producers are forced to live in the real world. There is no government support which makes it hard to litigate things, there are not really internationally famous porn stars complaining about piracy and, above all of that, it's a fiercely competitive industry so there's no room for DRM and the other poor decisons other companies make. They are forced to act in an economically sensible way, and complaining about or wasting time trying to recover sunk costs is not economically viable.