this take is irritating because it implies that people at companies don't have to bother being ethical or holding the people around them accountable at a personal level for being ethical, as if it's somehow predetermined by the environment, being at a corporation, how you behave.

Certainly it's true that the incentives of corporations push you to ignore ethics. But that's why they're ethics: they're precisely the things you should do that you don't have to do. That's what morality is. Sure, for the purposes of doing things about unethical companies, it might be best to view all corporations as fundamentally unethical because that implies that the right place to make society better is by opposing their behavior with laws. But at an everyday human level everyone is responsible for exactly the things that they do and being at a corporation in no way changes it at all.