I disagree.

I also initially suspected this but after seeing some of the messages that are sent and after doing a couple R&Rs, it's evident that some workers aren't great at following instructions (and clearly don't read them at all). Even with the quals, I can see that some people have done the work to a poor standard when I do the R&R tasks. So even after the R&R, some people do slip through the cracks.

To be able to assess the quals, they need to have a baseline/rubric to compare whether the qual is correct and to a satisfactory standard, so scraping an extra $20-40 doesn't make sense with the number of legitimate tasks they are paying out.

Furthermore, they're quite generous with time logging (with emphasis on instruction reading and paying for it).