In a criminal case, if you are charged with an assault, the state incurs the cost of your defense, should you be unable to provide one for yourself. In a civil case, no matter which side you are on, you always incur the legal costs yourself. Large media companies, the ones actually engaging in legal action (NOT the creators), often have to do little more than threaten a lawsuit (or send a cease and desist letter) to elicit the desired behavior, even if they think they can’t win in court, because they know the defendant lacks the financial resources to defend him/herself and will thus back off, even if legally they are not obliged to do so. Scanlators generally cannot defend themselves and often lack the necessary legal knowledge (or access to a professional) so as to ascertain which legal threats have teeth and which do not. There may be ways of doing scanlation without express permission that do not violate copyright; it’s likely we will never know what they are, since the publishers hold (nearly) all the cards.
Ba Zi, 9a. Copyright, Scanlation, and the Ethics of Unfettered Reading ift.tt/2aD6b7G