UK and Eire both entered EU on the same day so they could carry forward to a common trade policy to remove borders. If one of them decides to leave you cause a border. If you agree to be in same customs union with common goods rules then you either can vote and veto the rules or have rules imposed on you. So you either end up worse, or end up worse, or stay as is.
The sublime irony is basically because there are an illiberal party of 10 in NI propping up a conservative minority in UK the hard logic and truths will cause the ignorance to be corrected eventually with a change. Those harking back to an imaginary better past when there was an empire will be eventually not be here.
Most people here just want innovation, people and goods can move as freely as possible, good quality Anker products get to UK as cheap as possible with the fewest cost increases from localized rules.
Big nation's like USA can afford to have local rules because the effort to manufacture and test goods for those rules is diluted across a large market. The smaller your market for each set of rules the more you force either prices up or the seller gives up selling. This is why biggest markets are the cheapest.
In the UK history the way it got power was through wars and armies and won via oppression, owning half the world. Not sure we want to go back to that. If you know your history UK put an army in China once.