It costs almost nothing to run a crawler and host these mostly static clone pages. So yeah, if there is a $100 profit in this, someone will do it. Keep in mind there are still plenty of countries out there where the average wage is well bellow $1k. For many people, the "ad pennies" are worth it.
I've wondered this too, sometimes I land on one without ads and its a very high turnover, it's almost like there's a college course out there with the final project: "scrape and clone stackoverflow, grades will be proportional to web traffic you capture"
I don't understand why Google's engineers haven't figured out a solution to these. Other search engines, like Bing, do a better job.
It can't be that they don't see the problem themselves. I have trouble believing they're OK working on such a shoddy product or that they're told to leave it so shoddy (when they could probably work anywhere else). Maybe there is some technical challenge I'm missing.
Seriously. What's up with these websites that are copies of Github/stackoverflow with a different UI? Cash grab for ad pennies?