> It seems very hard.
Its not. From a most basic level you (whatever position you're in, I've been the laborer myself, later the foreman and more recently the superintendent, now the field engineer) must keep an eye out and do your part to first, instill the safety culture, secondly to enforce it and hit any lapses as soon as they happen (sit someone out, send them home, write them up) and third, show everyone that you fucking mean it and its not a bunch of empty words, typically, by pushing back against higher management when they're trying to push schedules and work loads down onto the field crews that aren't realistic.
Whether you're using emotional appeals with your field crews, pointing out that no one comes to work not to go home at the end of the day, and how harrowing it is to watch a friend get hurt or killed, how it'll effect their partners and families; or a hard nosed impersonal business logic to explain to schedulers that pushing the team won't make them any more productive, or to accountants that cutting the budget for cheaper PPE will only instill a bad taste, I can't deny it takes work. But again it isn't hard, in the end no one wants to get hurt. You have to get past that teenaged sense of invulnerability and get it into their heads that it can and will happen to them unless they're careful.
> Firing skilled laborers harms both the employer and the employee.
Crews come and go, grow and shrink. Firing a troublesome employee brings a lot less harm to both parties than someone getting hurt or killed.