That's fair enough Faith, but I've done loads of reading about this and I can't find any country that has completely open borders with another, completely separate country, without having very fixed trade and travel arrangements - and a fixed border or a physical border at some sort of "outer ring".
Canada is obviously different, because there is a physical border - the sea. Ukraine is different because they are trying to get closer to the EU, not move away from trade and travel freedoms.
Norway is in Schengen and in the Single Market, and there are very strict rules about goods entering EU from Norway. From what I've read the UK has rejected the idea of a Norway type deal because it's too restrictive for trade deals with other countries.
As mineallmine says, we in Ireland, north and Republic are worried. And our worries are in no way helped by the fact that May, Davis and half the British negotiating team don't seem to have any idea what they are saying, what they want, or whether their proposals (whatever they may be) are feasible.
Just saying "no hard border in Ireland" - "no different treatment for NI" - "no staying in the Customs Area" - "no Schengen" etc etc doesn't make us hopeful that they have any idea at all.