The manufacturers build the things on an expectation of no more than one day's battery life - doesn't matter who the manufacturer is. That's the trade-off between size/weight and battery life. Bigger battery = bigger and heavier device. People will accept greater weight if it comes with something else they want (usually, a bigger screen), but "only have to charge it every 48 hours" isn't high on the list. Why? The most convenient time to charge a portable device is when it doesn't have to be portable - when its owner is asleep. Since humans are on a 24-hour sleep cycle, it's both convenient and practical to tailor battery life (and user habits) to that same pattern. Even if battery life could be extended by 50%, nearly everyone would charge every night, to be sure to have a 100% full charge at the start of the day.
Generally, improvements in battery life and battery size are allocated to new ways to drain those batteries (additional features), rather than substantially extending battery life. If you want to extend battery life, the first place to look is the feature set of the device. Do you really need push email, or is a mail fetch every half-hour enough? How many apps really need to have your location updated throughout your day? Should you leave Bluetooth on all day, when you only use it for the half-hour you're in the car? If you have a bigger screen, maybe you can slightly reduce the brightness. And so on.
But for this particular user, the #1 adjustment to make is to when he charges his battery. Why is he charging before he goes to sleep? The phone will be active throughout the night, with little or no benefit to the user. Charge overnight, remove from charger at start of day = several hours of additional, productive usage on that very same charge, with no other attempts to improve battery life.
Why isn't he doing that now? Maybe he charges via USB, connected to a computer elsewhere in the house (syncing daily is a good thing, too). Obviously, he needs the phone by his night table, but it's inconvenient to unplug the Lighting cable every night and move it to the bedroom, then move it back to the computer the next day. Possible solutions include:
Buy another Lightning cable
Use Wi-Fi Sync (presuming a home Wi-Fi network) and relocate the Lighting cable and charger to the bedroom
Switch to iCloud for backups (again, presuming a home Wi-Fi network)