Re: Gorilla(s) in the room
Not sure where you are based, but in the UK this is certainly not the case.
Although most phones are sold by the networks it doesn't mean they are jumping for joy to be selling the iPhone over any other manufacturers. Customer behaviour does mean the network operators as a whole sell the most phones - simply because it's the simplest method for the customer phone up, new phone comes = no effort and it's effectively on credit without doing a thing.
The networks push new iPhones because they know that if they don't other networks will be happy to poach their customers, many have seen this happen multiple times in the early years.
The network operators would much rather sell you a non Apple phone that they have a much higher markup on. In fact most of the operators pay higher commission (or increase the banding - thus price to customer) . So yes, the iphone might get you to call the networks retention's department, however they will try and sell you something they make more money on once you have opened the door.
iPhone has a very slim markup for the operators. Tesco once let slip that the cost price wasn't even 10% below sale price, it's likely the main operators get a better deal - however Apple squeeze, so it won't be a massive amount more.