Why Always On The Center?

I also don't know why... maybe is British standard kali!!!
All my kampong house or my friends old or new house most of them I see their Fan switch is always on the center. I don't know when is this rule started lah but my house was build during late 70's already is like this.
Ya why oh??? why it always place at the center of the switch oh? If my children one day asking me this question you know what I'm going to tell them?
It sound funny but make sense....
Honey..... look up at the celling, you see the fan is it at the center of the celling? So that's it why the fan's switch is in the center lah!!
Now you got it why you and my fans 's switch alway in the center now? hehehe...