The problem is that a lot of businesses don't have time to wait for things to be ironed out. This is why every business group in the UK has been calling for clarity about the deal and the rules for the past four fucking years.
Most SMEs that go under are not making a loss, they go under because of cash flow problems. And it's not just companies that deal with the EU that are in danger, its companies that deal with companies that deal with the EU, and companies that deal with those companies, because when one goes under it causes a domino effect. Cash and goods get's locked in when a company goes in to administration, goods and money that belongs to their suppliers and customers so they in turn can't pay their bills either. Businesses are already runing on empty because of Covid, they don't have the capital to lay out until things are sorted out.
SMEs often settle their debts on a monthy basis (30 days net). 18 days have gone, that leaves 12 days to "iron out all the creases" before the dominos start to fall.
The first reply to the wine producers tweets from page 173 is:
"You mentioned 3 things brexiters dont understand that's cashflow, red tape and business". Truer words...