Police officers and soldiers are interesting in that they are expected to behave ethically even for things that there is no specific rule for. Police are much more lenient on their own so in reality inappropriate or unethical behavior has no consequence with soldiers it depends, do something inhumane to a POW, maybe nobody cares, associate with criminals and cheat(sexually) with other soldiers partners then even if there is no rule you might get discharged 'dishonorably' (they are expected to be honorable which often implies ethics). Cops might also run into situations where what is happening is legal but inaction might reasonably result in harm, so I think the ethical thing is to break the law and face consequences. They might also see something illegal (like other cops' crimes) and it might be legal to overlook that but unethical still. The key here is they are both given much power and leeway,they are expected to behave in a way that reflects the trust which includes ethical and honorable behavior.

In your truck driver scenario, the truck driver either did kr did not break the rules. Was it unethical if he lived far away? For him, no. For management that perhaps knowing the risks allowed the practice then they might have been unethical.