It is true, that the customer is never right. Presumably speaking from the retailer's point of view, they have specific rules and guidelines they have to follow like any other company in the world. You may think that USCC is not being as helpful to you as they could be, but only because the problem you experience is not in line with the steps needed to be taken by USCC employees.
As far as handsets go, you are given 30 days from the purchase of a new phone to return it at no obligation should you be unhappy with it. 30 days, in my opinion, is more than enough time to figure out of the handset you purchased is right for you. Sure, there could be a future update on the 31st day of owning your phone that completely screws it up and makes you feel like you were just jipped out of your money. Sadly, USCC does not have control over how the updates affect each phone. They do, however, test each update before letting it go live just to make sure there are no bugs, but typically the bugs found in updates that were previously deemed safe and ready are caused by the user for not taking the precautionary steps needed to succesfully update their device.
It is USCC's policy to help you in any way they can to get your device working at optimal efficiency. Should there be a problem that cannot be fixed remotely, they will help you in receiving a replacement phone via the manufacturer. By federal law, any company that sells a product that could have possible faulty hardware must offer a credit equal to the purchase price of the device that has been replaced a minimum of 3 (three) times according to the Lemon Law, which enables a consumer to receive aformentioned credit in exchange for the return of the faulty device. Afterwards, the credit can be applied to the a new or similar device, but they will require you to pay the difference of the retail price (i.e. you return the Mesmerize that you paid $100 for at the promotional price. You will be given a $100 credit towards a new phone at retail price. So if you want the Electrify, you will have to pay the difference of $500).
As for the retail cost of the phones, USCC (or any retail company for that matter) does pay around that price for their devices to sell. The upcharge is simply for the company to make money and also covers the cost of overhead (employees, service, rental, etc.)
When you way the good versus the bad, USCC always comes out as a top retailer.