in some countries' handwritings the digit one is not a vertical bar but it has a little ascending hook, like a digit seven turned vertical, but with a shorter roof.
so 'muricans mistook my German ones for sevens, all the time, and I had to force myself to write what looks like a pipe symbol vertical bar to me instead of my trusted one.
and to disambiguate, we cross the seven like a lower case eff or tee is crossed.
The handwriting of numbers and letters being confusing between countries is something that's easy to not think about until you've actually faced the issue multiple times.
I'm English, and I can't honestly remember which country it was that I've lived in (I think France...) where there were a couple of numbers that even after living there for a year I still wasn't confident reading when hand-written on things like café menus. And I don't think I would have thought of that being a systemic issue rather than just blaming an individual's handwriting before I lived there, despite having taken over 100 trips to France before moving to live there for a year.
so 'muricans mistook my German ones for sevens, all the time, and I had to force myself to write what looks like a pipe symbol vertical bar to me instead of my trusted one.
and to disambiguate, we cross the seven like a lower case eff or tee is crossed.