I don't know why this is the equilibrium in the economics job market, but employers get upward of 150 applications for one or two tenure-track teaching slots many places. The difficulty of getting any information from picking through them all, in a limited amount of time toward the end of the term, is immense.
No wonder that outcomes in job markets like this can be so random, or that such searches are costly in terms of time and energy for seeker and employer. What a tremendous burden during period of high unemployment such as now!