While I agree that, as a job seeker, this is annoying, it would also diminish the quality of jobs offered if each Employer had to post their compensation offers. Imagine the following scenarios:
I have $70,000 a year I am willing to spend on a qualified programmer, so I post a job and claim that amount is the compensation. I will get applicants with little or no qualifications who just see the $70,000 salary, and the ones I really want, who might be looking for a little more money, would pass me over. I spend time weeding through the unqualified applicants and never get a chance to offer the really good ones better compensation.
I have a programming job I need filled. Secretly (if you want to call it that) I am willing to give this person about $70,000 a year, if they meet my qualifications. I get applicants who are interested in doing the things I say I need them to do, and who can show me they know what they are doing. I have fewer unqualified applicants to deal with and more time to speak with the qualified ones and decide if I want to pay them more if they say they require more.
The last phase of any application for employment should be to talk about compensation, never the first.