Don't worry, my friend also find it out after one year. 
I also won't realise if i didn't add the fog light at my vios j.

I just found out today after 5 months. I actually tried the turn switch when I first drove it home but did not occur to me that it is for the rear fog since J spec does not have front fog light. I guess this is the problem with most of us for being too lazy to read the manual...LOL.