(edit: see my reply to your other comment. I think that one&#x27;s a bit better-structured to address the points you mention)<p>I don&#x27;t think it&#x27;s out of the question. Here are some good reasons why Facebook might <i>want</i> to structure their pipeline like this.<p>- Cellular Bandwidth is still expensive. They don&#x27;t want the reputation of raising your data bill by uploading all your photos. Maybe the GPU cycles really are cheaper. After all, Facebook already uses a lot of battery anyway; what does a few million more cycles per image matter?<p>- Messenger on iOS gets a new release every week. It&#x27;s not very difficult to make code changes. Not quite as easy as a webapp, but updating recognition models is a pain anyways, so it won&#x27;t happen too often.<p>- Uploading photos without the user&#x27;s consent is going to make Facebook look very bad, especially in certain countries like Germany or other parts of the EU. They already don&#x27;t have a lot of social &quot;privacy trust capital&quot; as it is; they might not want to waste even more &quot;trust capital&quot; on such a silly application.<p>Compare this to Apple, for example, who loudly claims that even they can&#x27;t read your encrypted iMessages. They do this to win privacy karma points. Sure, this claim may not be true, but Facebook can&#x27;t even consider this kind of marketing if photos are indeed being uploaded. On the other hand, if all the recognition happens on the device, Facebook could <i>win</i> some much-needed privacy karma points back by loudly saying so! Why wouldn&#x27;t Facebook want to be able to say this? It&#x27;s within their grasp, too!<p>I agree; I don&#x27;t <i>think</i> they&#x27;re doing this. But my argument is much weaker: I only claim that it&#x27;s <i>possible</i>, or perhaps even <i>reasonable</i> and <i>desirable</i>, to build their service like this.