This comment drastically underestimates the amount of capital spent on suppressing union activity, it's not as if they're operating in a vacuum.
For my coal mining grandfather, it meant safety equipment like respirators so you didn't get black lung, and that the company had to send down a meal for you if you were working a double (before that you had to rely on the next shift to give you items from their lunches, if they were willing to share).
We have OSHA for that today, so I don’t think the primary purpose of a union is to file OSHA complaints…
Who do you think lobbied to start OSHA? It was the unions.
But regardless of the history, it’s not longer especially relevant to the roles of unions today, and certainly adds nothing to the value unions supposedly provide to their members.
The question wasn't about what unions do today. The question specifically asked what unions were for. I stand by my statement that they were formed not only for pay increases, but also for working conditions improvements.