A menu price is not the cost of ingredients plus a margin. It is the output of several adjustments, and the ingredient cost is only the starting point.
Food cost sets the floor
Kitchens calculate the cost of a plate from a costed recipe, including trimmings and the portion of a bought ingredient that never reaches the dish.
That figure is then divided by a target percentage to give an indicative price, since ingredients typically account for a minority of what a restaurant must cover.
The remainder pays for labour, rent, energy, insurance and the losses on unsold stock, all of which continue whether or not any particular dish sells.
Labour intensity varies more than ingredients
Two dishes with identical ingredient cost can require very different amounts of skilled time, and the slower one occupies a station that could otherwise produce several covers.
Preparation done in advance is cheaper than work performed to order, which is why braises and confits appear on menus that also offer expensive à la minute dishes.
Kitchens therefore price against the constraint of the service period rather than against ingredient cost alone, because during a busy service the scarce resource is time at the pass.
Wastage is priced into the survivors
Perishable ingredients that do not sell are discarded, and that loss must be recovered somewhere on the menu.
Dishes sharing ingredients with several others carry less of this burden, since an unsold portion can be redirected. A dish with a unique perishable ingredient carries considerably more.
This is why menus consolidate around a limited ingredient list, and why a special using something bought specially is priced above what its recipe cost would imply.
Placement changes what people order
Diners read a menu in predictable patterns, and items placed at the top of a section or set apart from the list are chosen more often.
An expensive item can raise the perceived value of everything below it, so a high anchor may exist to shift attention rather than to sell in volume.
Restaurants track the sales mix and the margin of every dish together, and a popular low-margin dish is more often repriced or reworked than removed.
Drinks carry the business
Beverages, particularly wine and cocktails, generally return a much better margin than food, and they require little kitchen time.
This allows food to be priced closer to cost than it otherwise could be, which is why a restaurant's economics change sharply when guests drink less.
It also explains service formats built to encourage a drink before or after the meal, since the additional revenue arrives without adding load to the kitchen.