The "all electric" coach is probably a misnomer

The Hydrostatic heater (Burns Diesel or Electric) is common on Diesels. it also can "Burn" engine heat when you are on the road and pre-heat the engine before you leave in many cases., Very handy.

The rest.. Yes all of them can "Burn" diesel via the generator.. But then some places the stuff that comes out of that metal box next to your RV was made with fossil fuels.. INCLUDING in some rare cases Diesel. Just not YOUR diesel.