They do not receive employment permission solely through L dependent status.
Separate family involvement from authorization
L dependents may study while maintaining status, but study does not extend the stay or grant permission to work in a family business. The dependent category concerns a qualifying spouse or unmarried child under 21, each with actual status evidence.
The usual alternative for a student is a course of study with a school authorized to enrol foreign students, and that route has its own admission timetable, financial documentation and issuance steps. The practical consequence of the FAM position is that dependent periods must be provable rather than merely asserted: keep the dependent approval or the record of admission showing the classification, not simply a recollection that the family travelled together. If the spouse's employment is intended to continue beyond the assignment, an employer-sponsored route in the spouse's own right takes time to arrange and cannot sensibly be started in the final months. If the spouse's record or circumstances are unclear, resolve that question rather than trying to change the principal's job classification to obtain a different family result.