BST -- the following is just a guess, as I've never heard it justified by a SW program before, BUT I think that they don't require the GRE for two reasons.
1. A lot of the programs, even the in person programs, tend to accomodate people already in the field. This means non-trads (for all the bajillion reasons that non-trads go back). It may make the program more attractive to non-trads if they don't have to take some type of entrance exam. As a non-trad, I'd say this isn't particularly true for myself, but is for many of my fellow undergrads going back after a long absence. I tend to test well, and I'm certain I'll test well enough to get into masters programs. Doctorate no, but masters, yes. However, as a non-trad there is nothing like finally working your way through to the place where you need to be, despite all the hardships, only to find that there is a test, lurking there in the darkness, to judge your worthiness. It can cause a lot of stress.
2. My personal theory on WHY SW programs don't rely as heavily on the GRE is that it is because of their political/social justice ideology. Tests don't take into account the WHOLE individual. Tests can be slanted towards one population and scores don't represent the entire picture. I have not seen the statistics for how well the GRE predicts performance in grad school, but I'm guessing its not even close to 100% (my random guess would be not more than 66%). The last time I did research on how well entrance exams predict success -- it was on the ACT/SAT (back in 2002) and the percentage was right at or just less than 50%. I mean, really? All the while ACT claiming that they have a very high predictor rate. I had this discussion with one of my professors, and she stated the GRE folks are aware of the gap in prediction, and that's a partial reason for all the recent revisions. I feel like I should quote you some research, but really, I'm being lazy.
😛 Also, to be honest, its one of those topics that is so hotly debated I feel ridiculous quoting a study for, because someone else could just pull up 4 other studies that state something very nearly the opposite. There is SO much information on it, all I can say is you'll have to decide this one for yourself
🙂 Oh hey, so that I'm not so insanely lazy, here is the ACT's statement of predictive validity!
http://www.act.org/research/policymakers/pdf/PredictiveValidity.pdf
And here is the GRE's statement (that doesn't actually give you any numbers), but points you to more research.
http://www.ets.org/Media/Tests/GRE/pdf/gre_research_validity_data.pdf
In my nationwide search for high quality SW programs, I was really super surprised at the number of programs that didn't require any kind of entrance exam at all. There were a number of programs that did, like Hunter. But what I found to be more common, was that even respected state universities, even where EVERY OTHER master's program required some type of entrance exam, the SW was one of the lone wolves that did not. At first I attributed this to "suckiness" or "lame azz" programs, but really, in the end I think its more about ideology than anything else.
That said, I don't think that standardized entrance exams should be thrown completely out, but rather just looked at in the "whole picture" of things. I think not doing well on one can tell you just as much about the person as doing well on one -- but only in comparison to the rest of their CV. I'm one of those people that do REALLY well on multiple choice tests. I feel like I test better than what I actually represent -- so sometimes scores mis-represent you in the opposite way.
tl : dr version
In my personal opinion the social work programs that don't require the GRE do it for twofold reasons. Political/Social Justice ideology and to make themselves more attractive to people already in the field.
