Noncompete agreements, originally intended to keep skilled workers from bringing trade secrets from their employer to a competitor, are starting to show up in low-wage work. Companies are realizing that even where no significant trade secrets are at stake, they can keep workers from looking for other jobs by making them sign agreements putting many available jobs off limits. And Amazon is taking this logic to the extreme by making warehouse workers—even temporary ones—sign strict noncompete agreements.

This is even more extreme than the Jimmy John's noncompete agreements barring workers from getting jobs at basically anywhere else that sells sandwiches.
In many states, such agreements aren't enforceable. But if workers don't know that, it might be enough to scare them away from leaving a job where they've signed a noncompete in order to get a better job somewhere else.