How much of your cellphone bill is profit for the carrier?

I notice in Asia, people can buy the phone, then buy the service prepaid or monthly. I remember getting unlimited national phone calls and unlimited GSM/GPRS for US$25 a month.
This is so much better than in the US with 2 year plans, it hurts to think about it - even though phones are cheaper here with a 2 year plan.
There are only 4 bands in the world, so I don't know why US phones are locked. I hope the ignorant little people in the U.S. can see what happens in the rest of the world, then maybe such as choice will be available here.
Can someone explain the insanity?

The phone infrastructure also sucks here, I think China/Japan/Korea is already planning 4G networks (this is a different problem)

Also, can someone explain why designer jeans made in China will cost more in Shanghai than in California? This also doesn't make sense.

So why do I care about all this and telling the readers of THG?
The sucky wide area wireless broadband makes it almost impossible for UMPC (and smart phone) type devices to be used for accessing information anytime-anyplace. I don't want this infrastructure to slow down innovation and growth in other areas. I don't see a casual user spending $50 a month for a phone plan PLUS $60 for unlimited GPRS to make these new divices useful.

If I am completely wrong about all this, please let me know.

Thanks!