In practice, we use the term “labor market” because those words tend to go together, but if we take a moment to stop and imagine it was an actual “market” it would be a pretty crappy one. Imagine walking into a grocery store and milk was priced as “between $5 and $15”. You need to haggle on the final number. And that’s if you’re lucky to live in a state where prices have to be posted at all! You also don’t really know what’s in it. There is also considerable investment whether or not you end up liking the price. (Imagine you have to stand in line for an hour before you can even begin haggling.)

Anyone who has applied for a job knows that switching companies isn’t free, as it would be in a “free market”. There’s any number of outside factors that could prevent it. And switching too often is also viewed negatively, which is not true of e.g. shares of Amazon.