> Workers can as a group walk off the job. Workers are free to quit at any time.

Have you ever actually studied a labor action? How it happens? The power dynamic is vastly in the employers favor. By far the majority fail or are outright broken by targeted firings, strike breaking, etc.

> IME, that works much better than using the law to privilege either side.

You're begging the question that it currently doesn't favor a side.