In fact, the only animals protected by electric fences in Jurassic World are the non-violent herbivores. Even then, people in the command center still can't tell if a fence door is open or where the visitors' vehicles are (another feature Hammond has back in AOL days):
Hopefully that PC is preserved in amber somewhere and can be restored.
The Jurassic World big wigs do have one semi-innovative idea: microchipping the dinosaurs so they can track them ... and yet they manage to even fuck that up, because as soon as the indominus escapes her pen, she claws out the tracker. Unlike your local veterinarian, the geniuses at Jurassic World forgot to implant the animal's microchip in a place she can't actually reach.
And now you're imagining a T. rex trying to reach its back with its comically tiny hands.
Also, if the park is trying to save costs, why not relocate to a place like Florida instead of making everyone schlep out to an island in the middle of the Pacific? Plus, if the dinosaurs do escape there, that will only be the fourth-craziest thing to happen in Florida that week.