Where does the actual Kastoroff case belong in this continuum? It is--or is almost--a case in which the party injured by the mistake would be significantly disadvantaged if the contract were enforced; while, if the contract were not enforced, the other party would be no worse off than if the mistake had not been made.
The court does not say whether the school district had to open a new round of bids or not. If they did, they would have sustained those administrative costs, but would otherwise be no worse off than if the mistake had not been made.
In light of this, it is understandable that the court found that the contract was voidable.