The EU has been using the UK left-wing Remoaner press to try to undermine the UK negotiating positions, which is no real surprise.
The real danger for us where 44% of our exports go to the EU, sitting back and falling off a cliff will hurt us much more in the short term and the EU much more in the long term. We need a 2-3 year transition agreement as the changes are so profound.
Where we are in the Customs Union we are the frontline customs processing country for imports that arrive at the UK as their first port of call with us checking the origins of the goods and their compliance with EU standards and applying any tariffs and adding VAT. After this, there is complete freedom of movement of goods within the EU. After March 2019, we are outside of the Customs Union which means the first EU country we are exporting to has to do the full customs processing and likewise we will have to do the same with EU goods. There are many areas where we have given the EU complete control over standards and their administration. This varies from short term import/export of horses for racing, aircraft parts to the movement of nuclear materials.
To implement all our own versions of all of these changes can't be negotiated and implemented in 2 years, it is impossible hence the need for the transition agreement. Trying to muddle through will mean us falling off an unnecessary economic cliff and a severe recession for us and a recession for the remaining EU countries. We really need to avoid this.