Shaggy the evidence is because I have read it and watched it on the zillions of articles I have read on brexit. However I did I simple search on Google (which you were obviously too lazy to do). We are looking like 4 billion which is peanuts in relation to overall trade. The main markets for both the republic and NI are mainland Britain I did not need to google to find that out anyone with half a brain knows that. You will also note it sells sod all to the rest of the EU. Vish goods containers and otherwise could be dealt with via trusted supplier schemes and self assessment and spot audits. Exactly as most trade is done. The idea we need some special method to check the trade between the republic and NI is preposterous
https://fullfact.org/europe/irish-border-trade/ In 2016, 15% of Northern Irish sales and exports beyond its own geographical borders went to the Republic of Ireland. If we discount sales to the rest of the United Kingdom—counting just ‘exports’ to foreign countries—then 35% of Northern Irish exports are to the Republic."You will also note it sells sod all to the rest of the EU"N. Ireland sells £3billion worth of goods to the rest of the EU
In the event of a No Deal Brexit Britain will become a 3rd country operating under WTO rules with tariffs being applied along with customs checks and paperwork. Let's see how easy it is to export across the Irish border then. The EU have announced today that there will be a hard border in Ireland in the event of a No Deal Brexit. Unfortunately there are two sides to the Irish border.
Also at least 30,000 people travel over the border every day. That's over 10,000,000 journeys per year. How will the hard border affect us. Is that peanuts also?
As for the trusted supplier scheme and self assessment those ideas have already been blown out of the water a long time ago. If that was the solution we would already have a deal.
The idea you refuse to accept that there will be a border and the UK will no longer be a member of the EU and therefore a 3rd country is ludicrous. In the event of a No Deal Brexit everything will change utterly, pretending we can just continue as if nothing has changed is refusing to accept reality.