Prior to Apple launching the first iPhone, the business model for retailing cell phones was virtually 100% done by the carriers at retail stores. Carriers largely saw smartphones as inventory that they purchased from manufacturers which they certified for their networks, after which the phones were theirs to control. Meaning they had ultimate control over over the software and hardware of anything connecting to their service. OEMs really didn’t have an alternative to agreeing to that, since being denied certification would mean virtually zero phone sales.

When Apple wanted to enter the market, they didn’t want this to be the case. Their overall product strategy at the time (from computers to peripherals to iPods) was one of top to bottom Apple control of the experience. However they weren’t poised to start putting up their own cell towers. So unless they were happy with limiting their sales to just people willing to ditch their carries and sign up for a would-be Apple Mobile service, they were still going to have to rely on a mobile network partner. It was a conundrum.

They solved it, essentially, by choosing to go exclusively with one carrier at launch. They bet that the promise of exclusive access to iPhone inventory (and all the share of sales and new sign ups and retain customers that could come with it) would be enough to compel whichever carrier was most interested to drop some of their requirements for software oversight or interference. In the US, it was AT&T that agreed to those terms. After the iPhone was a hit, other carriers more or less agreed to the same thing, and it has remained that way to this day.

One of the key reasons why it has stayed this way, however, is not just the history. But rather, Apple’s strength in their own independent retail. Apple stores and their website account for enough of their iPhone sales that if one carrier wanted to play hardball and start insisting on dictating the schedule for updates, or preloading certain apps, Apple would be okay with halting iPhone sales through that carrier’s stores, and/or no longer activating iPhones on their network in Apple stores. That threat maintains the status quo.

Samsung, and other android OEMs, do not have that benefit. Both from the precedent of carrier oversight from the legacy era, as well as not having their own strength in independent retailing to effectively negotiate Apple-like control. Trying to get around that is one of the reasons that Google launched Google Fi, and why they offer such aggressive discounts/trade ins on Pixel phones through their own stores. However that’s still a fraction of overall Android phone sales.