Just from my observation, the Challenger was everywhere - and I mean in years afterward. Obviously it was commonly seen as a flashbulb incident.
Whereas, the Iraq War start isn’t mentioned or shown much in years going by.
In fact, I doubt I would remember it much if not for that waitress coming over to tell us the news. If we hadn’t been out to eat - I bet I’d have no special memory.
My daughter and I were on the way to Disneyworld when at a rest stop in Georgia a woman approached us and told us Reagan had just been shot.