What are the different patterns/quantity of employment according to demands of different income ranges?
So the phenomena you've identified is linked to a goods being labor intensive or not. Often ``craft'' goods required high-quality labor (think watches) to be built, while lower quality goods can be made using machinery. Now farming of all kinds used to be very labor intensive, but technology has replaced most of those workers. 

So the substitutability of a worker matters a lot here and the skills that luxury goods need may be less substitutable. 

Another factor is that when the good is more expensive, cutting costs (such as labor) at the potential expensive of quality is not always a goods idea - think how often you see ``handcrafted'' or pictures of the people working on the farm on organic products.