We might've been caught on different parts of the wave. I checked Ngrams out of curiosity
https://books.google.com/ngrams/graph?content=TUI&year_start...
Basically it was never used, then it was heavily used, and then never used, and then in the early 00s it took off again.
That'd explain why you used it, I never did, and now young kids are.
I don't think that search is very valid - the TUI group travel companies are likely much more mentioned than Terminal User Interface. They are pretty big around the world and have an airline, cruises, hotels etc.
Thanks for looking that up! It makes sense, of course - the line starts to drop in 1984, with the release of the Macintosh, and hits a trough around the launch of Windows 95.
It's not a term I recall hearing at all when I started using computers in the mid-'80s - all that mattered back then was "shiny new GUI, or the clunky old thing?" I really thought it was a retroneologism when I first heard it, maybe twenty years ago.