stupid Q: Rear brake pad smaller than front

[funnysam]

Just noticed that a lot of rear brake pads seems to be smaller than the front on a lot of cars.

For example, in my 2001, the rear pads doesnt even cover the entire surface area of the rotor, while the front does. Is there a reason for this?

Just seems wierd..to have a big rotor but small pad.
Are the front and rear caliber the same size? if so, can't we easily install bigger pads for the rear as well?

THANKS~~

[toyomoho]

Rear brakes only account for around 30% of the braking, thus no need for larger pads.