It's neither.... grant it the hinge/bushing may get a little corroded from salt etc.. but the paint chips fall off due to a simple cause..... Rocks from the tires.....
I am inclined to disagree with you as to the cause of the corrosion I am experiencing for a few simple reasons.
1) The corrosion is between the door and the hinge plate. No rocks will reach that area
2) If you track the pattern of road debris being flung up from your front tires, you'll see that the upper hinge of the front doors is not in that path.
You can see that three out of the four hinge plates per side are within the area that rocks/mud/road salt touches. Yet the upper front hinges are the ones I first noticed the corrosion on. Plus this would not account for the hood hinges.
3) On my two door, the barrels of all hinges were showing the bubbling, including that of the hood. Now, being as it was a 2007, I believe Chrysler knew of a problem with the paint, pre-2010. My current hinges aren't bubbling, but the white powder coming out from between the plate and the door skin indicates something is going on.
Either way, they are going to be pulled, stripped, and coated. The bare areas of the skins behind the plates will be lightly sanded clean and primed.
Plus, I like the look of black hardware on the orange Jeep.