Because the hiring process can be costly to the employer (whether or not the applicant is offered and whether or not the applicant accepts if offered), the employer is presumably concerned about yield… applicants seeking a higher pay level than the employer is likely to offer are unlikely to accept the offers, so they may not be worth trying to hire. On the other hand, an applicant with lower expectations may be easier to get if the employer’s offer is significantly higher than the applicant’s expectations.