Benny,
I posted this 2 days ago. This is why we would have to have a hard border (even if everyone says they don't want one):
Here is a little scenario that clearly sets this out.
Let's pretend that the UK (inc NI) leaves the Customs Union as they want to strike even better trade deals around the world; this after all was one of the drivers towards Brexit.
The UK enter into a Free Trade Agreement with Orangestan (a country somewhere far beyond the EU). In this FTA the UK can export stuff tariff free to Orangestan and Orangestan can export their oranges tariff free to the UK; again this is the Holy Grail of Brexit.
Compare this with the EU, who has an import tariff of 10 pence on each orange imported from Orangestan. So the Brexiteers were correct; they were able to negotiate better trade deals with Orangestan than the EU were able to.
Orangestan can deliver their oranges either to the port of Belfast or Dublin and the price, before duties, is £1 (Orangestan like sterling so they sell in GBP to all customers across the world!).
The price that Northern Ireland fruit wholesalers pay for the oranges are £1, while the price that the ROI fruit wholesales pay is £1.10. The 10 pence difference is due to the differential in tariffs.
Imagine there is no border.
What do we think will happen?
The oranges from Northern Ireland are likely to find their way over the border into the ROI because the NI oranges could be sold in the ROI at £1.05. This gives a profit to the people who had access to NI oranges, whilst at the same time ensuring that the ROI customer is making a saving on the price of the official duty paid product.
The greengrocers in Monaghan, Cavan and Donegal will see a reduction in their orange sales due to the inevitable smuggling of oranges. Soon the Northern Irish oranges find their way further south and this smuggling issue gets Leo Varadkar's attention.
The ROI greengrocers are up in arms because their orange sales have disappeared and import duties are not being properly assessed and paid over.
The Irish Government is faced with no choice, they have to install a manned border so that they can stop the orange smuggling route so that the Irish greengrocers can continue to make their living.
I appreciate that the above story may seem simplistic, but understanding this makes it very clear that the UK government is going to find it very difficult to actually get any sort of Brexit deal approved as Northern Ireland is such a burden on GB's desire to be free of the EU.
So think of this when we hear politicians saying that we need to negotiate a better deal with no NI backstop. It is just not possible; unless NI remains forever in the Customs Union - and it's difficult to see the British Parliament voting for that.
