Funnily enough, I've never needed to drive, which resulted in me never bothering to actually get a licence. So I'd have easily missed that memo at many points in my life. I don't need a licence to walk or ride a bike on roads where it might be valuable to expect everyone on them to understand the signage in non-opposing ways.
Now I'm gonna preface this with: I can comfortably pass a driving theory test with no issue whatsoever, before anyone assumes I'm coming from a place of complete ignorance.
Slashes, crosses & bars through something are commonly understood by everyone to kinda mean the opposite of the thing that's got a line through it. When a kid wants to erase a mistake in school, they're taught to cross it out. Basically making that concept intuitive to everyone who made it through the first year of school.
Now, when other circles with crosses, slashes and bars exist in the same signage design language, it heavily implies an icon in an open circle is intuitively a signal something is permitted and not prohibited.
The only people you can guarantee that a red circle means "don't" for, are people who have a driving license in a country that isn't the US
That's far from everyone out there. Which feels like a fairly clear failure for a sign that would typically be important
I've got some friends who work in corporate insurance, they get shipped all over the world, though still have to go to the office a couple of times a week when not away somewhere
I'm a software engineer and you can find yourself sent abroad for conferences or to do workshops with other teams in other offices (if you work for an international company). Though they're being a bit more pushy about getting people in the offices recently, so once again, not going to be necessarily 100% remote in that scenario (though some places manage to make it work)
I want you to know I'm not taking your request seriously lol