Comment by freework

You have to see it from th job hunter's perspective. It is very common to send out 20 resume's and maybe get a single response or two. It is very time consuming to write a custom multi-paragraph cover letter with every application. Eventually all job hunters learn that you get the same response rate when you write one sentence cover letters as you do when you put a lot of effort into them. Why spend so much effort when you don't have to?