Earlier quoted context omitted.
So you're saying that BSD has better power management than Linux? Would love to see some real research and analysis on this.
It's not a BSD vs. Linux thing. It's the entire software stack including user space, e.g. how much is the CPU woken up by silly background tasks doing useless things. That thing can be fixed regardless of the underlying kernel if people care enough . The total investment in desktop Linux is tiny compared to what Apple puts into macOS.
The vast majority of power management is less background services while active.
It's mostly about reducing idle power consumption sleep mode, and closed lid hibernation.
Most battery loss in mobile devices can be attributed to two things.
The screen, and how much is lost when the device is idle in your pocket/backpack.