Why is it so difficult? Essentially, because of the three things which Brexiters wanted, you could only ever have two:
1. The whole of the UK to leave the European Union on the same terms.
2. Leave the single market and the customs union, and
3. Avoid a border between the North and South of Ireland.
You cannot avoid having at least one of the three things which Brexiters didn't want:
A: leaving the EU and the customs union, means you have a border between North and South Ireland.
B: not having a border, means the UK would stay in the customs union.
C: Northern Ireland stays under some EU rules, meaning the whole of the UK didn't leave the EU on the same terms.
This is what the Northern Ireland protocol entails. Checks are made on goods travelling between the UK and Northern Ireland.
The disagreement is on how rigorously checks are made on goods between Northern Ireland and the rest of the UK.
","author_name":"Andrew Brown"}