Lowes doesn't install doors themselves; they have contractors in the area who come out and perform the installation. If your friend had a detail done by the Lowes contractor (where they come out, measure, inspect the frame area, etc.), it should be on them (Lowes and the installer) to rectify the situation; not the manufacturer (Jeldwin). If he ordered the door and didn't get a detail done, it's on him vs. Lowes. :shrug:
It's a small price to pay ($35) to ensure you get the right size you need, and remove yourself from the error equation if something does go wrong.