I can see stumbling around in the dark for a few days after an event like this, but the main story is supposed to take place 15 years after the lights go out. You’d expect anyone who has managed to survive that long to be fairly adept. Even the younger characters would be as good with the postindustrial technology as modern teens are with smart phones and computers.
The future isn’t what it used to be.
What slackers. The family of five in The Swiss Family Robinson had disassembled a shipwreck and built their treehouse with running water within days of their life changing "disaster". In their spare time, they hauled the ship's organ off the wreck and installed it into their treehouse for entertainment.