That's perhaps true to a small extent perhaps but I think simple economics have more explanatory power. Subsonic air travel is an 80/20 solution that meets the needs of a very large market. Once you can fly from New Your to London in 7-8 hours dropping the flight time to 3.5 hours has limited utility especially when you consider it does not drop overall travel time by anywhere near as much. For most passengers it's not worth the far greater cost to make SSTs safe.

The same thing applies in a much bigger way to travel to low-earth orbit. Costs escalate dramatically.

Maybe I am related, because I am also from Slovenia... ;-) Becuase we are a small nation (just 2 millions) I am very proud of him...