The OS on desktop situation isn't comparable to the OS on mobile situation. You can buy any PC and expect being able to replace its OS. On phones, you have to look for the ones where it's possible, and depending on the phone, it's possible despite the efforts from the manufacturers for not allowing it.

Also in PC OSs, there isn't a corporation dictating what programs you are allowed to install. In iOS there is, and soon in Android too.

IMO, these corporations have managed to amass an amount of power where there's no longer consumer freedom. Therefore, there's no free market. We have reached a point where the law must intervene to restore capitalism.