@Walter Hinteler,
The UK government now refers to no-deal Brexit as an "Australia-style deal" - Australia trades with the EU largely on WTO rules >
Framework Agreement between the European Union and its Member States, of the one part, and Australia, of the other part (currently under provisional application pending the completion of ratification procedures)
The EU is the UK's biggest single trading partner. In 2019, it accounted for:
43% of UK exports
51% of UK imports.
The EU is Australia's second largest trading partner, after China, and Australia is the EU's 18th.
Australia is on the other side of the world, whereas the UK is the EU's next-door neighbour. That means Australia doesn't rely on the EU in the way the UK does, for the operation of just-in-time supply chains in sectors such as cars, pharmaceuticals and food.
So border checks and delays have far less impact on EU-Australia trade than they would on EU-UK trade.
In other words, going to WTO rules for trade with the EU - without any other deals in place - would be a huge change.