>Surely every stakeholder has some degree of responsibility in the proper functioning of any system.
A civilization enforces responsibility through the law.
>I am free to degrade public infrastructure such as roads because it is not my responsibility to build them.
Yes. And either the government should set laws to prevent you from misusing the infrastructure, and/or the people should shun your company for being a bad actor. The former being consistent for infrastructure that is owned and maintained by the tax-funded government.
>I am morally justified in committing crimes since I am not a police officer.
Morality and legality are different things. Neither people nor corporations should be judged by the government through the abstract, subjective morality of individuals, only by agreed upon, written law, and at its loosest which is a court's interpretation of the law.
You as an individual can hold anyone responsible for anything under any criteria, but then you should state you're speaking for yourself as per your own moral code. As a society, we have rules for that.
If you want to make your moral code the law, then that should also be explicitly mentioned as such instead of speaking as if it's the status quo.