Re: Should not have Netherlands VAT ...
On the contrary I think I have been paying a lot more attention to this issue than I needed to, out of sheer fascination for the area and its history.
For instance I find it interesting how you completely obviate the importance and scope of the joint-rule arrangements that came from the GFA. Schooling, policing, energy, water, health, migration controls, agricultural policy alignment and coordination, etc. As the direct successor to Sunningdale, the treaty introduced a great deal of such joint, cross-border, power-sharing and mutual legal entanglement institutions, governance bodies, arbitration processes and mechanisms. So I am not buying your "it had nothing to do with anything" claim in the least. And maybe I should have evoked that level of complexity right away instead, fine.
There simply was no way to unwrap all of these complex, wide-ranging arrangements, and carve a border harder than anything that had existed there before, without voiding the treaty of basically 100% of its substance (and causing major constitutional headaches in both countries). That is why the Irish side of negotiations so firmly pressed the issue. And, Irish interests being European interests, and the EU being one of the signed guarantor of that treaty in the first place, obviously there was no going back on it.
So stop making this all about the IRA, that is ridiculous, and probably unhealthy too. Brexit was threatening many aspects of current NI-RoI governance if it was allowed to erect a border across Ireland, the peace process was secondary to it (and ideally should not even have come to the fore).
"The UK team took far too long to realise that the negotiations were with what amounted to a hostile power."
I think you are projecting here.
"No one in the mainstream UK parties is willing to "threaten the peace process", which is why the EU's move over the vaccines should have been taken as a golden opportunity to let them have as much rope as they needed."
That is delusional. Someone unfamiliar with the NI protocol forgot to recontextualise the exemption for NI in the draft document, Ireland pointed out the mistake and got it corrected. At no point was the UK in any position to "give the EU rope".