Zinc does conduct electricity, but only very weakly... so someone with boots could have safely crossed the roof...
Another solution would have been to drive up one of those pick-ups with the plastified (rubberized) loading area's (like the isuzu), and from there knock the person free... (as a car stands on rubber-tires most of the current would be neutralised, even when somebody would by mistake contact the roof)...
As an experienced person in "urgent medical help" I can say very few persons know how to perform cpr in a correct way, and doing it incorrectly can also kill... (or break ribs, etc...)
Matilda, I think general first aid classes, and general info sessions could help a lot, but then again, how many people would attend? As I explained in another thread, Acira and myself stopped at a nasty moto-accident a couple of months ago, checked all vital signs, immediately diagnosed one person as having at least a severe concussion, and then the fire-department showed up (supposedly pro's as they had the ambulance with all the flickering lights and let's not forget the sirens) and without checking one thing just threw the person onto a stretcher and carted him of...
My sincerest simpathies for the poor girl and her family