Why does the iPhone have terrible battery life?

My iPhone 5 doesn't last that long compared to my friend's Samsung S3. I looked the battery specs and the iphone is somewhere around 1450mah while the samsung is at 2100mah. This got me thinking, why doesn't Apple just put powerful batteries on the iphone?

Added (1). Yes I have turned everything off except for my cell phone signals and it sits there eating battery life away.

Added (2). Well Mr. AVDADDY, it seems that Apple has never done anything about it. There are forums filled with people complaining aobut it, when will they listen?

Added (3). Spacema… I have done everything that you have mentioned. I keep all apps off, keep the batteries as cool as possible. Yet it still doesn't help!

Reduces production cost, same thing with the accesories like earbuds and chargers

That is not the Apple way.

The capacities of the batteries alone can't provide
the necessary data for a useful comparison.

You would also have to figure out the actual power consumption of the device,
which will vary according to what it is doing and for what period of time.
(This is virtually impossible, so don't waste time trying to do it.)

Energy-saving tips:

Minimize the number of applications that are "on" but not being used.

Reduce the screen brightness to the lowest usable level.

Don't "fidget" with the phone:
Handling it so that its screen is lit up most of the time,
even though you aren't using it, is a huge drain on the battery.
Put it in a case (preferably) or a pocket, and leave it alone.

Shut it completely off (if possible) when you are sleeping,
and always shut it off when charging it.

Its because this is Apple's way to cut costs down. The iPhone was suppose to be over $500 but Apple deliberately kept the prices down to $199 (i think because of some negotiation of apple and at&t (the very first iphone. So each phone, Apple is at a loss. If Apple does upgrade the battery; per phone, the battery will be expensive (for apple, not for us) if they install a larger one. So basically Apple can upgrade the batteries but why should they when they are already at a huge loss.

I personally think that the Apple iPhone is no longer a good investment when you think about how good of a phone Samsung Galaxy is becoming. Both hardware and software wise, Samsung is really on the game here. Galaxy S4 or S3 is twice as fast as the iPhone and lasts twice as long. I was on the same debate as you are but I decided to trade my iPhone for a Samsung instead. I mean I want something that is worth my money rather than something that represents my status.

Iphone design doesn't burn battery like other phones, I can attach a car battery but that doesn't mean its better.