It's somewhat worrying that "prove you are not a computer" consists of the very same tasks we expect computers to excel at if we are to get self-driving vehicles.
Why is that worrying? We currently don't really have self-driving cars, in part because software is bad at interpreting images. The captchas are literally us teaching machine learning systems to do it better, because they currently can't. When computers can do it well, captchas will be different.
The only other real, scalable option is to verify identities (which is part of what recaptcha does) so this is the best we've got right now.
There was a time when basic OCR, clicking on pictures of cats among other animals and solving 5 + 7 was the gold standard for captcha. Now those challenges can be trivially solved by computers, and we have moved on to the current set. Very soon these will get outdated as well. This isn't worrying, just how technological progress works.