The world has a lot of different standards for a lot of things, but I have never heard of a place with the default screw thread direction being opposite.
So does each language have a fun mnemonic?
Photo credit: https://3.bp.blogspot.com/-Giy8OrYJTjw/Tfm9Ne5o5hI/AAAAAAAAAB4/c7uBLwjkl9c/s1600/scan0002.jpg
And you feel so incredibly dense every time you run into it and you can’t figure out what’s going on. The crank on my kids bike was out of whack the other week and I kept tightening it down and it kept coming back loose. I was turning the crank one way to tighten it which was pushing it against the lock nut but it needed to turn the other way to be pushed against the bearing before I tighten the lock nut down. If it was all right-handed it would have been clear what I was doing.
… and you hope you don’t forget until the next time you have to do it…
Spindles and shafting are places you can find left handed threads. And it depends on the direction of rotation like that bike crank. Can’t have things coming lose due to the way bike cranks turn, so they a left handed thread to stay tight.
It took me a long to time learn that when dealing with such things that I need to stop, look, and think about how things are assembled and why.