Utilities follow NESC, they have been able to dodge 70E for while now but are in the process of adapting many of the 70E rules. They also follow 1910.269 which has many of the same SWP's.
The only thing the 70E brings is the are flash calcs and PPE requirements. The tables only apply up to 38kV and the calcs dont work either, so really they ARE following the 70E, at least the parts that apply.
As far as PPE, linemen have been wearing arc resistant materials for years, but in the substations (Indoor, metal clad switchgear) the current rules the utilities follow are not good enough to protect workers, this is where they SHOULD be following 70E and this is where most of the upcoming NESC changes will apply.
The thing is, an arc flash at 72kV in open air is nothing compared to one at 480V in a cubic box with high available fault currents and a lonfg clearing time like what is found on nearly every 480V substation out there.
I hope I answered your question, if not, please ask a more specific question.