Marco Arment discusses the importance of including a salary range in a job post:
A job’s salary is one of the biggest factors in whether an applicant can or should consider it at all. It’s just as important as the physical location. Dan said he was hiring for a local-only position, so location is an essential eligibility requirement for him as the employer; similarly, salary determines whether the applicant can afford to take the job, so it’s an essential eligibility requirement for the applicant.
In practice, this is incredibly rare. If you are recruiting and want candidates to take your inquiries seriously, having a salary range will make a huge difference.