The first link mentions, "For editorial assignments, pay is often dictated by standard rates, but even those are somewhat flexible with added service fees (parking, mileage, rentals, digital transmit, etc). When it comes to commercial, corporate or institutional work, a dearth of information makes it difficult for both the photographer and the client to assess whether they are getting a fair deal". The article states it will try to gather pricing information from around the country, "we’re going to examine real world pricing by asking photographers around the country how they price specific jobs. The intent isn’t to single out a particular approach as being “correct,” but rather to show regional factors and the nuance that goes into pricing, and hopefully help start a more transparent dialog around pricing that can benefit photographers as a whole."
What they will find, like medical costs, is that regional cost of doing business differences, due to local salary standards and local rental market situation for commercial space, will reflect considerable differences in price for a given service...this is what Medicare reimbursements to medical practitioners are reflected via the 'geographic adjustment factor'. But in that case, it is the government forcing specific price factors on practitioners to accept, and it is not necessarily a mirror of actual operating cost differentials from town to town!
In the case of commercial photography, the 'day rate' concept is based upon the fact that set creation and lighting for product photography can be very time consuming activities as well as expensive undertakings, just to be able to take a photo! A half day or full day can be consumed merely in preparation to take the shot!
And while the actual product might only be a single photo for a catalog, the use of the photo, and the 'value' to the client can vary, so that 10000 copies of a brochure has a different perceived value to a company offering a high end piece of capital equipment sold to hundreds vs. one offering a $200 consumer product marketed to millions. So the 'use' of the photo can vary widely in the 'value' perceived by the client.
Today's portrait or event client's usual expectation of 'photos on CD' cuts into follow-on sales of prints by the photographer, making today's photographer not much more than an hourly-paid shutter finger in the client mind! As a result, if we have two photographers -- one a weekend warrior and the other a full time pro with lots of experience -- how does one justify in the client's mind why they should 'pay more' for the experienced professional vs. the almost-snapshooter approach of some weekend warriors?! Both have similar 'value' perceived by the client, while the 'cost' varies considerably to produce a photo that can be taken to Costco to print cheaply!