For god's sake, how many times do we have to go around this loop. The EU is not a single entity. It is 28 states and of the 27 excluding us, 20 of them need to agree the terms of the trade deal. Of the 27, the majority - like 24 or 25 - have nothing to gain from a trade agreement and plenty to lose.
Ask yourself this. When we say to Poland, "we're not allowing your citizens to come to the UK without visa restrictions, points-based, capped migration limits etc", but please will you agree to us having an open trade with you where our UK businesses are free to export to your markets without tarif and without the burden of EU employment laws". Why, why on earth, would they say "OK alright then"? Same for all the eastern EU nations.
Expecting a quick and easy trade negotiation is absolute fantasy and it honestly beggars belief that there's anybody who still clings to this fantasy. EVEN IF all the nations were broadly in support and agreeable, it would take years because the EU is like swimming in treacle at the best of times. But there is no such consensus. It will take YEARS to negotiate a deal. How can it not?