We just accept the “o’clock” thing. We say it, and we don’t give it a second thought.
Consider this thought number two.
It means “of clock,” right? Sometime in the olden days people would ask the time and other people would say, “It’s four of clock,” and that wasn’t weird to anybody? Wild.
On that topic: Is this what’s happening with Irish names, too? “Of Connor?” “Of Brien?” “Of Connell?” And did anyone else’s St. Patrick’s Day as a kid in grade school consist of making a locker nametag with an O’ in front of your last name? Joe O’Stunardi, for example. And did the kids with actual Irish last names have to put an extra O’ in front of theirs? I can’t remember if they did or didn’t at my school. I kind of think they did, though. I remember at least thinking about this. Back when I was six years old.