Your comment is at odds with itself. On the one hand, you say that if you don't like the working conditions, leave, on the other hand you point to one of the most unskilled and exploited labor positions (mining) as a good use for a union.
Which union do you think has more power: The AMA or a union for miners? In one, the employees are scarce, limited, and irreplaceable. In the other, the employees are numerous, easy to train, and very replaceable. Why would you try to justify a union for one and not the other when it's clear that there's no value in dealing with a mining union - it's cheaper to just bring in new employees.
Exactly, that was the point. Miners need unions more because it's easier for them to be exploited. They probably need legal protections because they aren't coming from positions with many valid choices.
On the other hand, tech workers aren't in a commonly harmful, let-alone fatal, profession and we enjoy pretty good mobility. We don't need unions half as much as we need to take a principled stand and vote with our feet.
Which union do you think has more power: The AMA or a union for miners? In one, the employees are scarce, limited, and irreplaceable. In the other, the employees are numerous, easy to train, and very replaceable. Why would you try to justify a union for one and not the other when it's clear that there's no value in dealing with a mining union - it's cheaper to just bring in new employees.