If you go to the other side of the door most of them will be exactly the opposite
I assume it's a standard for locks. That's been my experience anyway.
Clockwise motions have become synonymous with use for everything from valves to screws. It wasn't a convention people adopted from the start, but something that evolved over centuries. A bit like the symbols on things like music and video pla<x>yers which just evolved over time as manufacturers played with different ideas until eventually they invented extremely user friendly symbols even a novice could recognize immediately.<br />
The number of possible explanations for why clockwise won out boggles the imagination, but suffice it to say it had to do with the industrial revolution demanding more standardization.
It's because children are taught "Lefty loosey, tighty righty," when they learn to use a screwdriver, and that's carried over to locking a lock.
I think it is a practice from old times.Just as majority of us are right handed, this has become a de facto standard.