How about camera manufacturers? If someone uses a Nikon camera to create CSAM (“child porn”), should the Nikon company be liable to the victims? Cameras are made, by design, to produce images of what’s in front of them, even if that is a child being sexually abused. There have been proposals to require digital cameras to spy on their users to ensure that illegal images can be more easily tracked. If a camera manufacturer refuses to do this, citing “privacy” or “freedom of expression”, should the victims of CSAM be able to hold that manufacturer liable?
Some countries, such as the Soviet Union, have restricted the ownership and use of printing equipment, including photocopiers, to deter their use to spread illegal capitalist propaganda. Should photocopier manufacturers be held liable for illegal material that a user photocopies?
Or, sticking to the gun example — How about 3D printer manufacturers? 3D printers can be used to create illegal guns. If you use a 3D printer to illegally create a gun, should the 3D printer manufacturer be held liable?
Alternately, we could stick to considering people liable for the choices that they themselves make, and not for merely creating the opportunity for bad users to make bad choices.
Car manufacturers aren’t liable for every incident of drunk driving or every robbery getaway — but they are liable for defects in a car that cause it to go off accidentally. Similarly, gun manufacturers should be held responsible to ensure that guns work properly and do not go off accidentally, e.g. if a loaded gun is dropped.