Originally Posted by
bennos
There's a difference between searching for available inventory and booking it once found. It's entirely plausible that ITA has better searching algorithms than the airline websites (airline inventory searches are a notoriously difficult computational problem to solve), or that caches got in the way, or that the website had a bug, or that the website implemented a different search algorithm, etc. If for whatever reason the search doesn't find existing inventory then the frontend has no way to know to ask to book it.
Book With Matrix actually helped me "shake" a cheaper fare loose a few weeks ago. DL was trying to quote me a higher rate than I was seeing. I called in, they could only see the higher fare, but Book With Matrix led me to the fare in question (which I was then able to book via Delta.com, much to my shock). Someone was probably querying inventory differently.
Of course, another time in the last few weeks I was also able to find a fare on Matrix and the agent was able to see it as well, so there was probably just a gremlin in the system.