My wife was a foster care social worker for medically fragile children (and their siblings) for five years in NYC, all five burroughs. And a quite a few of them died during the adoption process from rare medical conditions. Now she works in a (poor) neighborhood clinic as a social work care manager. Fun fact: I designed a crappy $17k concrete bathtub during that NYC time period. So, we both had some low points back then.
From what I can tell, she is an ad-hoc life coach for people who should have never had children, and my (internal) justification for her job is to help sate the lower class and hold off a full-blown societal revolt.
And you can just about double-up the 40k estimate if your Bachelors is in Genetics, Clark. A Canadian Bachelors, even. Thank God.
The problem with low pay in social work is that A) it's a completely unessential job, and B) It is right up there with Home Economics are the Ur-M.R.S. degree. It was a borne out of a volunteer field for bored wives of professionals who didn't get paid anyway and a lot of the non-profits are still headed up by these old bats - to this very day.