The problem is that this wizardry is not usually user visible, and doesn't have much of a correlation with the device price or operating system. If anything, i

The problem is that this wizardry is not usually user visible, and doesn't have much of a correlation with the device price or operating system. If anything, it's even possible that the cheapest phone has the most engineering done on it to optimize the battery life, due to the fact that reducing the battery size (and resulting cheaper BOM) on a cheap device that has millions of units sold is worth the additional engineering time to reduce power consumption.