In the UK and US, trapped under the "third way" behemoth that New Labour and Clinton had set up. (Fundamentally, Obama just got lucky the bomb technically exploded under Bush.)
New Labour simply couldn't think beyond neoliberalism, it had been accepted as reality. Not as ideology, but as a simple fait-accompli.
Have a play with this blog: k-punk.org/ and read the bits on Labour. There was a piece that really drove this home for me, but I can't find it now. The most important thing to note, though, is that when Clinton and Blair took power for the "left" by accepting certain parts of their predecessor's project, they didn't set about trying to rebuild the left in a stronger position for the future. They didn't try to rebuild the trade unions, capitalize on the internet to set up an alternative media power-base, or anything else. They simply continued to manage the decline of the left that had begun under Thatcher/Reagan (Being a bit sentimental and cheeky here: Carter was a dyed in the wool neoliberal and Callaghan was forced by the IMF at proverbial and perhaps physical gunpoint - I mean, if they were plotting to coup Wilson…) accepting that it was inevitable and they had to work with it. Blair himself doubtless believed the problems of 1970s Britain were caused by trade union militancy and overspending, (as opposed to international energy and currency crises.)
Which is part of the problem. I mean, I hazard to say even your average communist prefers a Labour and to some extent Democrat government over a Conservative/Republican one, even if that Labour government has an awful policy platform. So when those parties are bled dry (as Labour was at the grassroots, can't comment on the democrats.) they take a lot of energy with them.
And since Labour (and the British press) still believe the "Too left wing" myth as the explanation for why Labour loses elections, getting a serious hearing for any alternative economic ideas is impossible. So they accept neoliberal ones a-priori, and Ed Miliband rides off into The Sun-light to be lanced by the Kinnock Effect.
Only tangentially related book, but very good. (Written by the guy who did the blog I linked.)
The ones who get credit usually made a falsifiable claim.
One look at the economies of many countries just before 2008 and you should've known there was a problem. (iirc at one point the Sydney housing market was worth more than a year of Australian GDP. If that's not a sign something has fucked up, I'm an anthropomorphic watermelon.)
There's no complete explanation, nor anything approximating the state of other sciences, but you can obtain a degree of predictive value in some hetorodox schools. (I mean, even proving that certain models don't work has value. Sraffa ftw, neoclassical school on suicide watch.)