twenty miles per gallon in a RV? Only on class B (van conversions) and even then a limited subset of small ones. I certainly would not want to do a 12k trip in one. Throw in that you only save over hotels if you don't stop anywhere because many campgrounds can be nearly half the price of a hotel if not similar depending on time of year.

then lets throw in reliability. there is so much more to break and none of it cheap to fix as outside of appliances most of it is unique to the manufacturer.

Class A (the big boys) are also a whole different world than B and C which are based on vehicles which have crash test regulation and protection. Class A and many Class C are sub 10 miles per gallon.

self driving long distance trucking is where its at. companies can absorb the cost much easier than individuals. as for the comment about liability, yeah I don't expect level 5 any time soon and even level 4 as an option.