I didn’t know it was possible to not know this.
Who taught you? I didn't know until my 20s and have met many adults who didn't know.
I've encountered a few cars where the arrow points to the wrong side, and it's quite subtle if no one tells you.
I'm in my 40s and just learned this right now.
Nobody ever told me and I drove my first car for a long time, rarely drove other people’s cars, and did not have the kind of lifestyle that either supported or required rental cars.
I found out around age 35, I think. From reading it online. I’ve told a bunch of people who didn’t know.