Internet Captchas (or Completely Automated Public Turing test to tell Computers and Humans Apart) most definitely have their place on the internet. They pretty much capture "bots" that have been developed to take advantage of many online scenarios. For instance, when you hop online to purchase concert tickets that might be sold out in minutes, a bot will be able to buy as many as a user wants at a fraction of the time a real human could ever possibly do.
However, if Captchas work so well, then why are they getting harder and harder?
As it turns out, Captchas had to evolve with time. It turns out, millions of people, who decoded warped text and isolated relevant images from a small gallery in order to pass the Captcha test, were indirectly training bots how to differentiate the right answers from the wrong ones.
We have now reached a point where around 33% of humans could pass a Capture test on the first try. However, bots have an accuracy of 99.8%.
So the solution? Well, a new Captcha system has now been implemented into Google which permanently tracks your online behaviour, regardless of what you do. The system now tracks your mouse movements, clicks, scrolling speed as well as your typing speed. If your activity seems suspicious to Google, such as if you were to constantly paste text into a paragraph as opposed to typing it, you may have to prove you're not a robot by undergoing another Captcha test, which now consists of a variety of Capture tests that are significantly harder to pass.
Take a look at the video below by the YouTube channel, Vox, on Why Captchas Are Getting Harder.