When you bleed the brakes in the "old" and wrong method(on a diagonally split system). which is exactly how you're supposed to do it on a front/rear split system. so going by that logic you bleed the rear circuit before the fronts.
So of course the rears are the furthest away. the fronts were on their own circuit, and the rears were on their own circuit. The only reason that the old "start with the wheel furthest from the MC" BS was started was because back in the day cars only had ONE type of brake hydraulic circuit.
not to mention locking up rear brakes would potentially spin you in a hurry, making the situation even worse. In a FWD car with a front/rear split, if you lost the front then you would lose about 70+% of your braking ability. The benefit to this is that you will only lose 50% of your braking ability should one circuit start leaking. and the right rear and left front circuits share the same port. The left rear and right front calipers are on the same circuit in the MC. not a front/rear split like cars of yester-year and most trucks/SUVs. it has a diagonally split brake hydraulic system. you "start at the wheel furthest away and work closer to the master cylinder." This does not apply to the Mazda 3. I'm sure you have heard when bleeding brakes.