-
The flatearth brexiteurs, John Redwood, Owen Paterson, probably Ian Duncan Smith
seem to believe that the UK can just walk away from the EU,
but planes will still fly, goods will still be imported/exported, international Post will still be delivered, because (rather like Dominic Raab and his bewilderment at the volume of goods/hgvs that flow through Dover-Calais), they have connotation of all the administration that is simplified by membership of the Single Market & the Customs Union.
What on earth do you mean, 'magically happen'? It's not 'magical' at all - if no one does anything, no deal is agreed upon, and if no deal is agreed upon, there we have the 'no-deal' scenario. It's not an actual 'option', it's the default that happens if nothing else happens, the one option no one has to do anything for. That's the threat of the deadline there.