What 3' rule? There is no such rule for receptacles. See Section 406.8(C). Inside the space, sure, but where does the space end? 3' out? I don't think so. The bathtub and shower space stops at the end of the bathtub (or shower floor).
#116006 - 01/29/0406:54 PMRe: Pool + Shower Locations
There used to be what was refered to as the "3' rule" for outlets near sinks and the like, to be GFI'ed. It may have been re-worded, or moved in the Code. It was pretty early in the GFI requirements. I'm sure that was what Sparky was refering to, as it read very simular to that other code in motor homes.
Now get this, where I'M at... ( S.F. CA - That's right, we publish our own Code Book here, welcome to the City. And all ten Inspectors interpit it differently. ) You can get hit by the AHJ for for "within reach of the tub", to be GFI'ed. This goes for line side of a switch, sconces or fixtures below 8', and of course, outlets. ( You'll only get hit on it if it's really obvious. ) After dealing with some "San Fiasco's", you get frustrated. So, I go through this everytime I do a switch, or light near a tub. I say to myself, " F%#*, GFI the WHOLE Bathroom. At the Breakers!"