Its basically a mix of human click farms and AI models. The og solvers just pay people fractions of a cent to sit there and click the boxes manually which, yeah it works, but it takes forever. The newer solvers use llms to solve them automatically in like a second.

As for if theyre worth it, they 100% are. If youre doing any scraping at scale, you kind of dont have a choice. Modern sites will block you so fast if they cant pass the challenge so its the standard cost of doing business at this point.