"Just following orders" is not a valid excuse.

Besides, one reason why they can be coerced is because these actions aren't clearly illegal. If they are, the employee can just report what they're being asked to do to the police. Workplace safety has been dramatically improved in western countries simply by making many unsafe practices illegal and creating entities to report illegal work to. While this did require criminal charges for some managers and employees, because safety has improved so much, they're really not that common.

I remember when I had workplace safety training as a poorly paid university lab monitor. They made clear that I had potential criminal legal liability if I allowed egregiously unsafe things to happen. So they didn't.