Most Android devices--and certainly all the good ones--are almost as locked down as iOS: Android has a bit more extensibility points, and sideloading has fewer restrictions, but it isn't like an Android device is some open "run anything you want" playing field (hell: the original Android G1 needed a jailbreak!!); and, really, if you analyze that market carefully, Samsung pretty much owns it with like 95% of the profit made across all vendors (and they have extra locked down devices).
Huh?... developer mode on an Android device doesn't even give you root access (which isn't that powerful these days due to SELinux), much less "infinite control": if you want to modify the lock screen or how notifications work or any other myriad things that Android doesn't provide extensibility points for, you need to jailbreak your device, just as you would for iOS. Some devices provide the ability to do an official "bootloader unlock", which actually gives you real control, but the vast majority do not.
(aside) The lack of basic understanding of how all of these restrictions work is so annoyingly pervasive that I have seriously been in arguments with people at conferences who are adamant about how open these Android devices are, and then when I challenge them what device they have they have a jailbroken Samsung on Verizon (the worst combo) and I have to walk them down memory lane to remind them of what exploit they must have downloaded (as I used to know most of the key players; I've taken a step back from the DEFCON scene, though, as the toxicity was getting to me).
Google, Samsung, Lenovo, and Nokia all support unlocking and flashing, including AOSP builds that are rootable. Yes, if you want to root your phones specific image you'll need to tweak it to support root.
