A big issue relates to the sensitive situation in which NI maintains economic activity. As previous posters have pointed out, ever since the Troubles, no politician has wanted to pass legislation that might lead to unemployment.
Like much of the rest of the UK and RoI, NI lost most of its heavy industrial base during the twentieth century. To keep things fluid, shall we say, politicians both sides of the Irish Sea were happy to let the public sector grow substantially. Today, NI has a duplicate all of it's own for every Whitehall department.
Whereas around 19% of the UK's total workforce (GB+NI) works in the public sector, in NI it's more the 30%. By comparison, about 24% of Scotland's workforce is in the public sector. Very roughly, about one fifth of Northern Ireland's entire economic output is generated by the province's own public sector activity.
At the sharp end of things, this means that NI is remarkable as a small region which has almost 100% "public" public transport. There are a few regional operators who run commuter buses into Belfast and Dublin, and there is a privately run bus from Derry to the two Belfast airports, but that's about it. Translink run everything: Metro (formerly Citybus), Ulsterbus and NIR. And while my friends and family in NI never stop complaining about the state of public transport in the province, I find that it is still astonishingly comprehensive (reliable, if infrequent, Ulsterbus service to almost every village and town) and affordable.