Why charge a upgrade fee?

I know when you go to a store to purchase new plan or upgrade phone they charge you a 35.00 fee for each phone you upgrade. When you plan on doing 4 or more phones that fee should be waived or adjusted to a flat fee of 80 or 100.00? But what if you do it online through the website and have the devices shipped to you. Does that fee still apply? I am trying to way out my options before I upgrade my currents devices?  Its not tike they have to do much work. The Phones transfer all the info for you. All the store reps have to do is scan the new phones and the required info for their service to know what phone you have and what line its too. and then the Samsung phone will switch all your information over tot he new phone. 

Gracias