I don't want to eat there, and I'm not guessing.
$5 average for snacks is actually a little low, but even a Mickey Ice Cream bar is $5, so that's where most people looking at the value of a dining plan put the value of a snack credit. When you subtract $10 from the $52.50 of a QSDP and then divide the remaining by two, you get $21.25. That's math, not guessing. Now, do most people spend $21.25 on a QS meal? I doubt it, but that is the relative value of the QS meal when you use a QSDP.
Then you take the $75.49 price of the DDP, subtract the $10 snack and the $21.25 QS meal, and you end up with $43.24 for a TS meal.
I'm not saying that's what people purchase, but it is the relative VALUE of the individual components of a dining plan.