The supersonic passenger flight thing is the one I have to really chuckle at. Nothing against the work being done in this area--hey, not my money. But effectively you have lots of folks, who probably mostly fly coach, super-excited that maybe one day CEOs and high-end lawyers will once again be able to fly from NY to London to have lunch, shake hands on a deal, and be home in time for dinner.

The passenger flight thing is the one I have to really chuckle at. Nothing against the work being done in this area--hey, not my money. But effectively you have lots of folks, who probably mostly take trains, super-excited that maybe one day CEOs and high-end lawyers will be able to fly from NY to London.

France is actually doing something very sensible here (banning domestic flight between cities if the travel time by train is under 2.5 hrs):

https://www.bbc.com/news/world-europe-56716708

why is that sensible?

Yeah. If there's good train service, it probably makes more sense to take the train. But if I'm flying through a city to get to another city, switching transportation modes can be a pain. e.g. Normally I'd take a train from (downtown) Manhattan to (downtown) Philadelphia. But if I'm flying into a NYC airport on my way to Philadelphia, that's a terrific hassle especially with luggage.