As the pay gets lower and lower, the quality of work received as a whole decreases. I have no doubt that the mystery shopping company in question is having issues with shops done incorrectly or poorly. They took a project that used to pay quite a bit more with another mystery shopping company. They're trying to get the same work done and pay very little considering the amount of work.
These questions are a feeble attempt to try to increase the quality of the work received without increasing the pay. It's saddens me that shoppers take these shops and reward the company for their behavior.
However, we can complain and moan and complain and all of that. As long as people continue to take the shops, nothing will change. From what I see, however, quite a few of these shops just don't get done. It's possible that they have a new contract that does not require 100% completion. It might not even require anything close to 100% completion, because I know they're not getting anywhere near that.