Your response to Imaging Sizing Problems and Solutions in the May 2007 ShutterBug Digital Help was a bit off the mark. Brian Sayler documented that printing 4X6 prints with his Epson R800 resulted in losing 10-15% from the edges. When printing borderless prints, the Epson print driver automatically enlarges the image to bleed the edges. The driver driver defaults to a conservative amount which results in losing quite a bit of the image. This value works regardless of the alignment of the paper in the printer. You can adjust the amount by changing the Expansion value under the Page Layout tab on the Print Properties dialog box. The Min setting results in barely noticable loss of content. Of course, if your paper isn't perfectly aligned in the printer, you may see some white on teh edges. Other Epson printers work the same way, including the large format printers such as the Pro Stylus 4800. I print a lot of 4X6 borderless prints and I am very pleased with the Epson R800 print quality and the felxibility of the provided software drivers. It doesn't take long to get used to leaving a tiny bit of room when cropping your images.
I can only assume that the Walmart and other kiosk printers use a similar approach to producing prints.
I hope this is helpful to the reader.