In a hybrid, the electric motor(s) can be spun as generators, and the electomagnetic force slows you down. About 50% of the time, you are slowing without any brake pads touching anything, front, or rear.
You have 4 wheel discs.
The rear is a "drum in hat" type brake.
There is a drum brake inside the rear disc brake.
The drum brake is only used with the hand brake ( parking brake ).
The parking brake ( the drum in hat ) is the one the sticks and or drags sometimes ( sometimes often ) and makes squeaks or sounds. I rarely use my hand brake, so I don't hear the sounds. People who use the hand brake all the time tend to hear sounds more often. Sometimes when the hand brake is applied, it does not release all the way.
Since you have 4 wheel hydraulic brakes, these work like a regular car when the stopping power of the electric motor is not enough, or your battery is full. Like a regular car, more weight is in front, so the front usually does more of the stopping.
HOWEVER... ususally, the motor is working in tandem with the disc brake, since the transmission is up front, and the rear disc brake works alone. SO overall, the rear gets about the same wear and tear as the front.
Ford initially expected the rear pads to wear out sooner.
In real life, I have never found this to be true.
In my car, and from everyone I talk to, a four brake pads wear about the same.
Does that clear it up, or confuse you more?

-John