I've had this problem a lot when I use a VPN. You're served a captcha that is impossible (I choose all of the correct squares and it still fails), and then I'm given a captcha with the ultra-slow click and reload images. At this point, I think it's more of an IP rate limiter than a human-bot detector.

but then some other services don't degrade like that and still offer you some easy 2-step puzzle "rotate a pic until panda is not upside down" or "find a panda"

Yes, due to the emergence of better bots, traditional CAPTCHAs aren't very good at being CAPTCHAs anymore either. It's a hard problem to solve, and it's a moving target.