According to news, Britain are insisting on a deal before they leave the EU and the British prime minister is suffering various allegations from distant past and being generally scape goated by the media for seemingly not seeing this as practical.
Might be the UK want to avoid tariffs that apply to any goods crossing eu external borders but It is supposed that the customs union falls under the umbrella of the world trade organization. The WTO constructs sanctions for any country that might oppose autocracy.
Is it feasible for the eu to continue to allow the UK to dominate the customs union?