I returned to my car at 12:50 AM at the airport after being away for 8 days to find a dead car battery (left the interior light on when getting all my luggage out)in my Honda Hybrid. Despite the hybrid having an expensive, humongous high-voltage, high-amperage battery to run an electric motor, there is no thought given to using it to back-up the plain old 12-volt battery used to start the motor. Probably this is intentional to keep it from ever being fully discharged.
A fellow passenger kindly hooked up his jump-pack, as he had had a similar problem himself and wanted a way to be able to get himself going without relying on someone else. He had stopped carrying jumper cables.
His jump-pack was dead; his chagrin palpable.
My jumper cables got the car fired right up.
The jump-packs do require regular recharging/checking; they're something else to check once a month. I've got more than enough of other things to do that I don't need to add that annoyance.
I'll stick with the jumper cables for my needs, as it's rare that I'm not around someone else. If I was way off in the boonies by myself, then I might make the financial plunge.
Sometimes, it does "take a village".
Or, I coulda just called AAA.