Reportedly, this training of bots is a thing of the past. Google used to do this, make people put in the street numbers from Street View or blurred words from book scans. But from what I read this isn’t really necessary any more, AI and computer vision got better and what we see these days is just wasted effort, it doesn’t contribute to anything except tell if you’re able to solve the challenge. I wonder why they still do all the zebra crossings and motorcycles and fire hydrants, though.