Ignore, for the moment, all the issues attached to anything other than trade.  On the trade side alone, the lack of a deal with the EU to handle trade amounts to more than just “additional paperwork.”  Because the UK has been part of the EU for so long, with seamless trading in place with zero tariffs, no customs checks, no paperwork, limited services barriers, ease of moment of people and so forth, this situation feels normal.  In a hard Brexit scenario, none of these conditions will apply. As many firms outside the EU would be happy to describe, doing business with the EU can be a complicated and costly process.  Tariffs into the EU for non-member firms can be high.  The customs and compliance formalities are tricky.  Most UK companies currently meet EU standards for products, but should expect significantly greater inspections at the border.