Any user, even with a carrier-locked phone, can download a file to his computer and use free utilities to install that on his phone. It's my understanding that

Any user, even with a carrier-locked phone, can download a file to his computer and use free utilities to install that on his phone. It's my understanding that the process is even easier than this. If you alter one option in the phone's settings, you can install Android programs downloaded directly through the phone's web browser -- no additional hardware needed.