Pay Transparency and Assumptions

There was a news story on this morning about how some cities are having trouble hiring enough people - specifically young people - for some summer programs. One of the things they didn't mention is what these jobs pay. I then ran across some posts on Facebook where our own city is looking for lifeguards, swimming instructors, and seasonal maintenance, But again, no mention of pay or pay range.

Who does post jobs with the starting pay or pay range? The businesses that are paying well. So what are we left to assume about job postings with no posted pay range? I'm not saying the pay is bad - I'm just saying that people are going to assume it is because they don't have evidence otherwise.

What assumptions do people make about something you are trying to accomplish because you aren't providing enough information?