I feel that's not right either. Apple did not physically build the phone network and nobody is piggybacking on their network, Apple isn't hosting anyone's photos or videos afaict and the user pays for bandwidth, they maybe pay for notification relay to their own users.

It's more like phone manufacturer X that accesses Ma Bell's network creates phone with slightly better call quality that only works with other X phones and is worse with anyone else's phones. And they start doing that once they have >50% market share.