How can the EU's border control be the UK's problem?
We are asking them to create an exception to their rules which doesn't exist anywhere else, and providing no realistic way in which it could be implemented while still keeping control of their own borders, migration, standards etc, and not discriminating against the rest of their population (part of the treaties and rules in place). Do you really think that the other 26 countries (who all have to agree) would be happy with and accept that one particular country in the group gets to put special rules in place which disadvantage their own citizens?
I can say "I want a car which produces 300BHP, does 100mpg, and costs £10,000 new. The car dealer down the road wants one to sell to me, too." Is it the manufacturer's problem to try to build one? Is the manufacturer being difficult or unfair when he tells me it's impossible?