Greed? You better believe it!
I'm going to date myself when I say this ,but I remember back in the early fifties reading an article in( I believe ) Popular Mechanics about a guy named Charles Pogue, an inventor from Canada. He came up with a single barrel carburetor,that when placed on(if memory serves)a 1947 Mercury sedan with a V-8 engine that,on a trip from northern B.C. to Seattle,WA and back,averaged 257MilesPerGallon of gasoline! And the country he travelled over for this test was definitely not flat ground fer shure.
There was a diagram of this carb in the article that showed it was a simple matter of forcing the liquid gasoline to be aireated to the extreme before entering the engine cylinders to be burnt.
No more was heard from Mr. Pogue for about a year. Then I caught a followup article that stated he was paid a huge sum of money contributed by oil companies and several auto Mfg's for the rights to his invention. One of the stipulations for this payment, was that he be totally silent about this and remove himself from the public eye. It went on to say he was living in the Canadian wilderness in a log "home"(not 'cabin') and had,indeed,removed himself from civilization. Rumors also had it,that he was warned of bodily harm if he didn't cooperate.
It goes without saying that this "invention" also "disappeared" from the face of the Earth!
Imho,until this sort of attitude can be changed regarding the huge conglomerates that control oil prices/useage, or, better yet, "removed" from what's under the Big Wigs' bonnets, oil will be slurped-up at their will and "we" will pay the consequences until fossil fuel is history...

(rantedy-rant over)