Rekognition crawled and annotated millions of images of different celebrities to train their face recognition model. Once you have an accurate model for a lot of classes it's much easier to add new ones with just a few samples.
This is pretty cool. Do you know of any good references for stuff like this? Not sure what the right topic name would be: online learning? streaming?
This is a good start
[0] https://www.mathworks.com/help/nnet/examples/transfer-learni...