Fridge contemplation. Really just need to go camping.

While underway, the fridge operates fine when off level due to the motion and vibration of the vehicle. A level switch would likely be turning the fridge on and off frequently in that situation, and that of course, would not be good. There are some makes/models with an "out of level" indicator though. Both Dometic and Norcold say that if the RV is level enough for comfortably moving about, the fridge is level enough.