Even President Trump made a slip and called the date 7-11 not 9-11.
https://www.snopes.com/fact-check/donald-trump-7-11/
It has been 18 years since that happened. I wonder how many people have been born since 9-11-2001? How many were even old enough then to understand it, live through it.
I remember where I was on that date, far from home, not being able to sleep, I turned on the news and saw the news and woke up my husband. We stayed up until the last tower fell, packed up and drove to the nearest military installation (I have contacts). Then we stayed there until things started calming down. Commercial airlines/airports were shut down and many people were stranded and the phones were flooded. We had a van, so we found people that were heading in our direction, piled them in with their belongings, women and children. And drove 2,000 miles dropping people off as we went. Now I will never forget that. I knew how bad it was as soon as I saw the planes and the first strike. I grew up around jets and know what a fully fueled jet crash looks like.
I will never understand what people went through when Japan attacked Pearl Harbor; but the relatives back a generation did and shared their experiences and feelings. If your experience with an event is just through books, news, etc., long after the fact, it will never be the same as talking to various people from many walks of life or living it yourself.