Re: less-noisy maybe but still un-sound
You should maybe do a bit more research... The US government sponsored Boeing's SST (Boeing 2707) project.
The difference is that in the US, environmentalists were concerned about the ozone layer (because of the cruise altitude of the proposed jet) and the sonic booms, and became more and more vocal until it became untenable for the US government to continue. In the UK and France there were no such concerns, probably because for them the primary market was intercontinental across oceans, whereas in the US it would have been transcontinental mostly across land, which would have had a much wider effect when it comes to noise pollution (well, sonic bang pollution for that matter).
In the British press you can still today see that sonic booms are a thing, as whenever an RAF jet has to be scrambled because of some airliner being incommunicado or in trouble, the Beeb and others go absolutely gaga over the bangs people heard, and the RAF having to explain yet again that yes, one of their jets caused a boom.
Ironically, the Port Authority of New York tried to get Concorde banned (and succeeded in delaying its entry into JFK for years) over noise. But when actual tests were done, it was discovered that Concorde on approach was quieter than the jets of the day, and it was only the departures at after burner that would be absolutely teeth-rattling. PANY lost, Concorde got to fly into JFK, but BA and Air France both came up with approaches and procedures together with JFK to make it as quiet as possible (so not all of wider Brooklyn, Queens and the rest of Long Island were hammered with noise 8 times a day).