No that's right, unions can't prevent layoffs or office closures, the idea isn't to prevent any sort of changes. To use a programming metaphor, it's more about

No that's right, unions can't prevent layoffs or office closures, the idea isn't to prevent any sort of changes. To use a programming metaphor, it's more about avoiding undefined behavior. We use contracts to define professional relationships in almost all other contexts; employment relationships are unusual in having terms that are largely unspecified. A union is just a framework for negotiating a contract. It does two unique, significant things: it allows for negotiating a contract that covers a group of workers (rather than an individual), and it requires the company to negotiate in good faith (they can't just refuse to agree to a contract at all). The contract itself is the important part, and the details are going to vary based on the situation. A $1M minimum salary wouldn't make sense at a tech company, but is reasonable in the NBA. On relocations, you're probably not going to forbid them, but maybe you have some specified amount of severance for this situation for people who can't move to the new location. Or maybe there's a minimum amount of notice the company needs to provide, so people don't have to pull their kids out of school in the middle of the year or whatever. I don't see why it would necessarily reduce mobility. I think it would make the company a more appealing place to work, so perhaps people would be more likely to stay at a unionized shop, but I don't think that's really all that different from someone staying at Google because they like the office cafeteria. Mostly, though, I think a union is not as extreme of a change as it's sometimes portrayed. It can't make money appear out of thin air, or turn around a failing company or industry, but it also doesn't prevent innovation or remove the flexibility to reward high performance. It's just a way for employees to put themselves on more equal footing with the company when setting employment terms.