I don't know what year your Runner is, but on my 2001 the Drivers window switch in the master switch and the Pass switch on the Pass side light up.
When you hit the window lock button, the Pass side switch light turns off but the drivers stays lit.
So passengers cant find the switch in the dark and know the windows are locked.
I think almost all new cars have this feature. Lots on new cars have all 4 switches illuminated too. I don't think they explain it in the owners manual either.
Do you want the part numbers for the bulbs from the dealer?