A good thread by @pmdfoster and @paulrey99 but I believe both miss an important point. It's not just about "they don't want to make it work". It's possibly also that making it work would not be legitimate.
To explain that: The border question is about identity and ideology, something what Brexiters should know all to well.
Fact is, The solutions discussed, even if they work on a technical level at one point in the future, mean more visibility of a border. Not just in form of cameras but also in peoples' minds. The border will be perceived as more apparent. And this opens a can of worms.
GFA just works because both sides of the fight get what they want. The border, neither in mind nor physically is barely (if at all) visible. Irish claims over NI are still seen as legitimate from Republicans and the Irish side, while the other side deny those claims.
That it doesn't lead to an open fight is due to very few differences. EU provides legal continuity if you cross the border and physical infrastructure is rare. It doesn't matter much on which side of the border you live - the difference is barely feelable.
Hence identity is an issue. Whether or not something is compatible with group identity is a matter of this particular group and making a more apparent difference towards NI and IE will be most likely seen as an attack on their identity.
The thing with legitimacy is, that it is at best interpersonal but never something objective. The fact that a part of UK is in Ireland can be easily interpret as a illegitimate occupation - to a good chunk of people it felt like that.
The point is that sharing a similar regulatory and customs framework made a "illegitimate" state tolerable, hence it was possible to agree to it. But the claim of Ireland being a part of UK doesn't become more legitimate because of that.
That means, every step you undertake in order to separate NI further from Ireland is going to lead to less tolerance towards the illegitimacy of this separation.
So why on earth should the Irish government agree to reinforce a state which a good chunk of people see as illegitimate anyway? Obviously I might get something wrong, but I think this is the gist of the matter.
This btw is also the problem of DUP. They see NI as an legitimate, integral part of UK and any border as intolerable. There is on the legitimacy dimension virtually no difference between Republicans and IE over land border compared to Unionist on sea border.
Hence the comments as "there are already checks between GB and NI" don't fly. The border between GB and NI would become apparent, a threat to their identity. Obviously, difference is DUP campaigned to change status quo, the other side didn't. Hence their request...
... is to me of less relevance or priority. The point is that a apparent border between GB and NI would mean to them that NI becomes less of a part of UK which is seen as illegitimate since NI is integral and legitimate part of UK.
I don't see how MaxFac can fix that. One side needs to get screwed, and let's be frank, EU has the cards and will force it through.
Besides, I recommend @Muinchille and @KeohaneDan on Tweets on NI.
