Please note that the Concorde requirement was set circa 1958-60, and the plane first flew in 1969; airlines were placing orders in the early 1970s.

Back in those days, airline security was a lot more relaxed: despite numerous hijackings nobody had yet figured out that a couple of hundred tons of airliner and jet fuel made a potent self-guided cruise missile, so the usual ending of a hijacking was on the ground with a negotiated hand-over. It was still possible to get from drop-off at the airport to the Concorde departure lounge in under 30 minutes; and for the trip from Arrivals at JFK to Wall Street ... well, that's what helicopters are for. (If you can afford a Concorde ticket you can afford a helicopter limo service!)

The immediate aftermath of 9/11 pushed the suggested minimum check-in time for trans-Atlantic flights up from 30-40 minutes to 3 hours, for everyone, VIP's included. So the folks who could afford a first class ticket -- the only kind of seat available on Concorde -- decamped for NetJets and other bizjet services, because the civil aviation security regulations didn't apply to private jets and you could still do the 30 minute from door-to-plane thing.

(And then Airbus refused to renew Concorde's type certification at the 30 year mark, allegedly just as they were discussing development of a new second-generation SST with a large Japanese corporation ...)

Actually, airport security -- at least for international flights -- in the late 60s and early 70s was not more relaxed. Having traveled quite a bit as a child in those days, most international travel involved having all your bags searched by hand in front of you. The difference was that air traffic volumes were much lower, you spent less time in queues, and Concorde passengers were first class and got preferential treatment.

The lightest airport security in my experience was in the mid-to-late 90s following deregulation. I flew from Sydney to Zurich in 1998 without breaking stride at either end (literally waved through every checkpoint).

Haha, yeah... in the early '90s I was late to the airport flying out of Berlin (to Edinburgh), arriving like 10 minutes before the scheduled time... I ran like nuts to the gate, and although they were clearly furious with me, and I got a ... very personal (but fast) ... security examination, and they still let me on the plane!! [Luckily I had no baggage to check.]

That was admittedly pretty ridiculous, but they were generally a bit lax back then. I thought it was actually rather odd because there had been a number of incidents, like Lockerbie, and the gulf war was a thing, and people actually were sort of worried about airplane terrorism. Not worried enough I guess...

9/11 only affected Concorde to the extent that there was a slump in the whole airline industry. It's not like people fled that plane in particular for bizjets due to waiting times.

The immediate impetus for retiring the plane seems to have been the prohibitive cost of rewiring on the whole fleet, to bring it into compliance with stricter modern requirements.

It didn't help matters when one of the Concordes briefly caught fire over the Atlantic due to an electrical short, something that was only discovered after the fact.

It's all in the thread, man!

I flew in 2003. Car dropped me off in front of the "Concorde" sign at JFK. I walked in the door, checked in, went through security, and then sat in the Concorde room until departure. It was far less than 30 minutes!