Batteries are still expensive. An iPad battery for instance is easily in the 100~200 bucks, same for laptops. The iPhone might come lower (50?) but even with a

Batteries are still expensive. An iPad battery for instance is easily in the 100~200 bucks, same for laptops. The iPhone might come lower (50?) but even with a simple system, opening the device will till probably enough of a friction to not make it worth it to most people. To make a comparison to cameras, I don't know how many people care to buy spare batteries outside of pros and people actually going through 2 or 3 batteries on their trips. Everyone else is probably using the one coming with their camera until it dies and then replaces it.