[alex_mathews]

The carriers subsidize the phone for new customers because they know they'll make the money back and more when you're their customer.

The ESN locking is an interesting way to enforce this, because the CDMA carriers also do 1 or 2 year contracts to keep you around. The GSM carriers do the same type of thing with locking the phone to a carrier specific SIM card and contracts.

I agree that it shouldn't be that difficult, but it's like this purely because of the business model of all the carriers. At least that's my view of things in the US.