EUG-LAS has been operated in the past by other airlines. I believe one operator was scheduled charters offered by FunJet. I'm not sure why the route has remained empty. It could be a good opportunity.
FAT-LAS was a very competitive route for AWX, fighting both Allegiant and UAExpress (3 daily Brasilias). Allegiant is Fresno based and involved in the community and UA started operating in Fresno in the late 1940s so they have always had a large frequent flyer base for UAExpress. AWX had only a single mid-day flight so it did not even connect with the late night bank, let alone provide a good departure time (i.e. late afternoon for after work or early AM for a full day of gambling) for LAS bound travellers who had other choices.
"Travel is fatal to prejudice, bigotry, and narrow-mindedness." - Mark Twain