And let's add to that that T:Group, in the case of Pilas of Lightning, Balls of Abysmal Flame and Lightning Bolts is the item created and not the individuals on the receiving end of those things. I had some trouble coming to this understanding myself. Ben McFarland and I had ample discussion about this.
T:Group versions of the aforementioned spells need to be designed with parameters that clearly lay out how the individuals )of the Form) are created (10 in a straight line, in a circle, 2x5 formation, etc) and any variation from that parameter involves a finesse spell, so you can actually pick out separate things of the same type, because the type of the underlying Form is the thing created, not the type or relationship of the recipient of the spell.
Of course, YSMV. But in a scenario where a magus who can cast T:Group Pila of Fire and can only see one person, well that one person gets 10 Pila of Fire, depending upon the success of the finesse roll to vary it from the original design parameters.