You type your password carefully the first time - wrong. You type it even more carefully the second time - still wrong. By the third try, you're meticulously pecking each key like you're defusing a bomb.
Meanwhile, the website's code is sitting there like: "Oh, you typed that password too quickly? Must be a bot. REJECTED!"
Seven years of development experience and I still can't convince a login form I'm human. Next they'll ask me to identify traffic lights in blurry images while standing on one foot and reciting pi to 100 digits.