I'd guess that the very large majority of people don't know that americans use 12h time, no. Why would they?
It is a bit strange, like being surprised some countries drive on the left side. xkcd 1053 of course, but people are still allowed to be surprised when someone went their entire life without picking up a fairly common factoid.
alt Hacker News
It is a bit strange, like being surprised some countries drive on the left side. xkcd 1053 of course, but people are still allowed to be surprised when someone went their entire life without picking up a fairly common factoid.