I am not a RV Tech but I have a theory about RV and S&B appliances and high failure rates. A very small number of users and a very large number of manufacturers have the feeling that using the latest in solid state/digital electronics enhances the appliances. In plain language, those little gadgets you see attached to the PC boards are not intended to operate, say, in the control panel of a range in the direct path of the cast off heat from the oven or a fridge in the compartment of an RV that is exposed to the elements. These components would operate much better and there would be far fewer failures if most of the useless functions(like failure codes)were eliminated and top quality parts were used. The shift from copper and brass to aluminum components, crimped fittings instead of threaded fittings and all the other improvements that seem to be the big problem areas in RV appliances were reversed, I think we would have better equipment.
Mil Specs are stringent for a reason.
And to answer your question, NO. MH equipment probably fails at the same rate as towed vehicle equipment.