What's particularly degrading is when it asks you to do something like "select all the bridges" and you as a human see one that is clearly an overpass, not a bridge. You don't select it because it's not what you'd call a bridge. You're inhuman.

You're asked to select the motorcycles.. Here's a motorised scooter that looks a lot like a motorcycle. You thought that wasn't a motorcycle? Back to the training camps with you until you start to think like a human.

Now select all the mountains. Huh? That raised mound of grass doesn't look like a mountain to you? Guess again, inhuman scum.

At least with the "audio captcha" I feel like I might be contributing to some closed captions for another human :(