I have to think it's marketing on two levels;
1). to get more people to click ads (for the reason you describe), and;
2). to encourage others to advertise, (as in -- "See how many clicks you're missing").
In regards to non-techies -- yes, and I can't believe how many of them I talk to, (potential web dev customers), and when I walk them through a search and mention listings at the top of the page and right column are ads, many say they didn't know that...