I guess u mean the City, Civics and the Jazz.. Yes all along
disc brakes are reserved for the higher end model car. But now
Totoya has changed the game rule by installing disc brakes in all
it model lineup. Like yourself, when you are buying a car, you
starts to consider all this factor.
Disc brake normally has better stopping power than drum. However,
disc pad tend to wear out faster and need replacement earlier.
Guess if you do not speed often, the front disc + rear drum setup
are already doing a good job stopping your car.
BTW, even disc brake has 2 types - ventilated and non-ventilated.
The earlier type is built in design to cool down the disc metal
since heat is a obstacle for braking. Next time, take a closer look
into the car disc brake and you will see the differences.
Just my contribution...