But I think the charging more for the stall for recognized does have a lot to do with the fixed costs of a recognized show over a schooling show (the TD, EMT, and USDF/USEF fees that a schooling show doesn't pay, plus a recognized show usually brings in a judge from elsewhere rather than use someone local). To cover those increased costs, the show needs to either increase the stall fees, or increase the class fees over schooling show prices. It is easier to base a budget on the increase for the stalls, because almost everyone will get a stall (at least in our area, we don't have day haul-ins) and it is difficult to predict how many classes will be entered.
For dressage shows, some people only ride one test a day, some ride two tests a day, and for the lower levels, some ride three a day! So it's hard to predict how many total rides you will have in a day in order to determine
the per-class price. If the per-class charge goes up, people don't enter as many classes, and then your predictions will be way off.
It's easier to treat a stall as a fixed cost to absorb the extra fees that a recognized show requires. Especially when the more rides a show has, the more fees have to be paid to USEF, so it eats into the increased price. But no matter how many rides a person does, they still need a stall.
You have to balance the needs of the show with the needs of the competitor. The competitors would rather have more classes for the same money, so it's better to increase the stall fees rather than the per-class fees.
Look at it this way:
If you normally show where it's $75/stall and $35/ride for 4 rides per weekend, that costs you $215. If a show has 50 riders, that means $10,750 to the show.
Say a show has to increase costs $20 per rider. That would either be a $5 increase per class (based on 4 rides per weekend), or $20 per stall.
If the class fees go to $40, and the stall stays the same, then the competitor's cost would be $235 for a stall and 4 classes. (X50=$11,750 to the show if all competitors can pay the increase) But if the competitors can't pay more than that $215 they had budgeted, then they can get a stall and only 3 classes for $195. With 50 riders, the show now only makes $9750, and has to find 10 more horses to enter to make up that $2000 loss from the estimate of $235 per horse. (And they have still lost $1000 from the original income of the show.)
If instead the stall fee goes to $95, and the class fees stay at $35, the competitor can still get 3 rides and a stall, and pay $210. The show gets $10,500, and only needs 6 more horses to make up the $1250 difference. (And they have only lost $250 from the original income.)
So both sides have to compromise. The competitor has to ride one test less than the original example, but still gets 3 rides and a stall for under $215 in the two scenarios.
The show gets more money if the increase is added to the stall instead of the class fees, but without an increase in the number of competitors, the show loses money in both cases.
The only way the show wins is if the competitors can pay the full increase and still ride the same 4 rides.