edit - Why was I voted down? Is it bad to ask questions? I thought others might be curious about this too. (BTW, thanks for the answer.)
Whether companies can implement things like eFuse or whatever is generally the realm of antitrust law, which is another ball of wax entirely.
"On EFF's request, the Librarian of Congress renewed a 2006 rule exempting cell phone unlocking so handsets can be used with other telecommunications carriers. Cell phone unlockers have been successfully sued under the DMCA, even though there is no copyright infringement involved in the unlocking. Digital locks on cell phones make it harder to resell, reuse, or recycle the handset, prompting EFF to ask for renewal of this rule on behalf of our clients, The Wireless Alliance, ReCellular and Flipswap. However, the 2009 rule has been modified so that it only applies to used mobile phones, not new ones."