It's because Apple is both a hardware and a software company. This gives them tight integration between the hardware and software to optimize things. They only have to write code for a very limited set of chips and screens. So they can perform custom tuning. And yet, Apple is notorious for poor battery life.
It's sort of like comparing a Porsche 911 to the rest of the automotive market. yes, the Porsche can do some things very well. But it's ill suited to other tasks like off-road or people or cargo carrying. Android has options in all parts of the market.
Benchmarks don't usually reflect a lot of real world use. They're fun for quantifying certain aspects of a device, but they don't show a complete picture. Just as hardware specifications aren't everything either.
Why benchmark scores don’t matter | Pocketnow
What do you want your phone to do and how do you want to do it. The market offers many possible Android solutions to that set of questions. Apple tells you what you want to do and how it must be done. And that is the core difference between an apple device and its use and an Android device and its use.