Working is frowned upoun for Royal wives - I think they are supposed to drop out of any career they have and go to "work" for the "family business" hnadling royal visits, etc until they are ready to pop out the Heir and the Spare. There's also the negative publicity for anyone who employs them ("Business XYZ is cashing in on royal connections through having Kate/Chelsy working for them") and the intrusion/disruption that the press would cause and the sensationist headlines that would be inevitable. Any attempts by these girls to "go it alone" and start a business of their own (no matter how large or small that business was) would also be accused of "cashing in" and again, you'd have the tabloids scruitinising every single piece of paperwork they could get their hands on, every single disgruntled former employee, and every report into the financial stability of the business being published with gleeful headlines about how crap it's doing and how it's doomed to fail.

Sometimes I pretend to be normal (but then it gets boring so I go back to being me)  Ylsuper