residential refrigerator vs rv gas/electric refrigerator?

I go dry camping quite a bit and love the gas fridge in my old Travel Trailer for those times. I would hate having a all electric one.

Unfortunately , on my brothers new 5th wheel he can't seem to keep his fridge cold with his gas fridge. I plan to start a new thread on it this winter and see if we can trace down the problem. I'm starting to thing that some of the new gas fridges are just poorly designed.