I never suggested this at all. I am just saying that there are externalities that our work generates and we should be critical of that instead of pretending that it doesn't matter.
As for the examples you gave, I think it's pretty obvious that there is a major qualitative difference between manufacturing rope and designing weapons that are regularly used to kill people. One provides general utility and the other is specifically designed to mame and kill.
> Does that mean it's unethical to work for a paint thinner company?
Yeah why not? Shouldn't we be trying to manufacture non-toxic chemicals that don't poison people and the planet. People working at those companies arent solely responsible by any means but that doesn't mean that their actions don't have serious negative affects on society and the planet.
Also cars are bad for many more reasons that just accident. Cars are loud, they pollute, they take up valuable space. Building roads and parking lots to support them destroyed entire neighborhoods, historic buildings and public space. They also isolate people, encourage wasteful sprawling urban design, and make it more difficult for disabled people to get around. The list goes on and on