As an English-trained lawyer, I am used to seeing a decision of the UK Supreme Court (or formerly, the House of Lords) published within roughly a year in Appeal Cases (AC) (and sooner in the Weekly Law Reports [WLR]) by the Incorporated Council of Law Reporting. Other common-law jurisdictions of which I'm aware (such as in Australia's High Court with the Commonwealth Law Reports [CLR])
I was surprsied to learn, however, that the decisions of the Supreme Court of the United States (SCOTUS) take a very long time to be published in United States Reports (US). According to the website of SCOTUS, the current volume of US is only current to 2014 (!). This means that there are cases which, six years later, still haven't been officially published and must be cited as 575 US ____ (2015).
Given the enormous resources of the federal government (which enormously dwarf the ICLR's, for example), and the relatively small amount of work it takes to typeset and copy-edit slip opinions, why does the US take so long compared to other common-law jurisdictions to publish the decisions of its highest court?
(Note: I tried to add a 'law reporting' tag, but had insufficient reputation; I would be grateful if someone could do this on my behalf)