I always just assumed these were terrible. There just isn’t enough info in a photo, even for the world’s leading calorie counting expert, to give a sensible estimate of the calories content. Ans even more so for macros. Add to that the fact vision is still pretty crap and you have a complete joke that I can’t believe anyone is paying for.
I suspect many of the results dieters get is “mere measurement”, e.g. it helps them be more thoughtful, seek education, etc.
So the value of the tool is in its ability to keep them engaged and hopeful (the unstated need), and the actual mechanic doesn’t have to be that good at the stated need.