Proof of work login instead of captcha

Question

I've just seen this genius script on github:

https://github.com/jsavoie/proof-of-work-login

My question is: Why is POW login not a world standard right now in 2018? It's absolute Genius!

Why are old fashioned captchas and recaptchas still so widespread?

Answer 1

The current going rate for reCaptcha solves is upwards of $3 per 1000. Meanwhile, the going rate for a t2.large spot instance is 2.78 cents per hour, dual cores with burst capability. So, for a proof of work to have the same attack cost as reCaptcha, the POW would have to take well over a minute, maybe two, on a single core of 3GHz. You're looking at possibly as much as 5min on an iphone 6. Most users would prefer to click signs.