Why does each IPhone have its own charger?

This has been bugging me forever. I have noticed that each IPhone has its own different charge cable. The reason i have noticed this is because at school, students always come into the office asking if i have a IPhone 5 or a IPhone 4 charger. Why does each IPhone model have its own charger? I mean if you look at Samsung phones, Samsung smartphones all share one charger. Why is it different with Apple?

It has to be a certain cable and input jack.

They don't all have different ones, the old phones can all share the regular one, and the 5 has the lightning which is way better

Apple has changed the charger plug over time, making them smaller and smaller.

They don't, you have the old or new. New charges way faster and is better.

There are two different types of chargers:
The ones apple has been using for awhile now (iphone 4 version)
and the lighting cable charger (iphone 5)
The 5 one is simply the updated form. It's smaller, and is supposed to charge faster.
I ASSUME apple is going to continue to use this model for the next few iphones so eventually the 4 one will be nearly extinct. Just wait… We're just currently in that awkward transition phase from old technology to new technology.

Because apple is difficult and greedy. Always try to find new ways to get our money

That's not the case though.

2G, 3G, 3GS, 4, 4S - 30-pin connector
5, 5c, 5s - Lightning cable

So among the 8 iPhone models there have only been 2 revisions to the charger.

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