It all comes down to engine bypass ratio: the engine manufacturers have been struggling to increase the bypass ratio on their jets beyond 3:1, and that means that unless the aircraft are flying very high (impracticable for short-haul use where they wouldn't have time to climb to cruise altitude) efficiency is much worse than a propfan/turboprop. It doesn't help that there have been a number of disasters on the way that would have almost worked - GE had nightmares and almost exited the jet engine business in the early 1950s when they tried to get a two shaft engine into production, Rolls Royce went bankrupt and folded after the composite fan blade disaster in the 1970s, and P&W are currently in Chapter 11 protection after the failure of the geared turbofan system. These would all have allowed step changes in bypass ratio (to be fair the GE two shaft idea eventually did), but the pain the companies went through trying to get there meant that trying to get investment in a new high-bypass jet engine is almost impossible so progress is very slow indeed.
Interestingly Whittle was predicting that jets would get up to 10:1 bypass ratios back in the late 1940s, if that had actually come to pass then the turboprop/propfan would never have happened - you could have done everything with bypass jets at higher speeds and vastly cheaper than at present. That would have all sorts of fascinating implications - imagine being able to fly from London to Los Angeles nonstop rather than having to stop to refuel in Canada on the way, or affordable transatlantic flights that take 8 rather than 24 hours.