PhotoLab needs a user-configurable preference for controlling whether exported files are saved with lowercase (.jpg) or uppercase (.JPG) file extensions. This should be an easy thing to add, but in the absence of a preference the program should at least default to the same case used by the source files being exported (export .CR2 as .JPG, export .cr2 as .jpg).
Photo Mechanic has such a preference and Photoshop still had one last I checked (I fired Adobe years ago). All professional imaging software should include such a preference, IMHO. Overlooking it detracts from the user experience and makes the program seem less polished.