I've seen this as well even on newer jeeps than mine, I have a '98. I can only figure that maybe salt added to never washing it and maybe being parked for a long period of time might contribute to it? Or maybe salt water from being close to the ocean over time? I've also noticed the tubs on these jeeps are also having rust issues and the rear gate hinges are usually badly corroded as well.
I am in the Kansas City area. We do get salt here. I like to keep things clean under the body but I guess lots of folks never give that a thought. I was just curious. I have not found that problem near so common on the older YJ's
I will have to find TJ and have a look see sometime. Thinking of buying one in fact.
I saw a slew of that myself before I bought Bonnie. It can happen from the hood rubbing the top of the fender or not cleaning under the wheel wells enough. That area gets hit from everything that rolls off the tires. If the rest of the jeep is in great condition use it to talk em down 400-1000 then just put the saved money towards tubes
2002 TJ Sport 4.0
3" AEV/OME lifted