>>1699821Development of new airliners is expensive, and you really do need decently high volumes to make up the cost. Tickets would go for a lot, but R&D costs would be high, fixed costs would be high, operating costs would likely be high, without passenger throughput or sales volume being high enough to make up for it. The practicalities of air travel (airport processing, airspace clearance, etc.) would also give it a theoretical performance vastly higher than actual performance, and higher costs than it needs to have or could recover.
Even in militaries, which are less sensitive to these sorts of considerations, aircraft speeds have more or less stalled out. The B-21 and H-20 are subsonic. Supercruise is more widely deployed but top speeds and operating speeds aren't really changed.
