The ball might be 40 billion dollars, which is not all that much compared to the over 1 trillion in trade germany alone does, and certainly less than Japan-EU trade deal offers, an trade deal with a country which is a tiny island somewhere afar from europe, same as the UK.
And although switzerland has a unique deal, that same deal was on offer to the UK and was turned down by the UK, since it is of course based on the 4 freedoms including the freedom of movement. Yes, the swiss voted to have that particular freedom reduced, and that was quietly dropped by them again after it was made very clear that switzerland would lose complete access to everything EU if they insisted on that, which is of course their free choice to do.
Do they expect UK to recognise EASA licences after Brexit and KLM be allowed to land at LHR when EASA licences issued the day before to UK operators do not allow BA to land at AMS?
Actually, no, they don't. Not because of licenses, because EU licenses will still be based on EU law, unlike UK ones (and if any UK license/passport states EU regs it is clearly invalid), but because the UK will not be part of the EU-Open Sky agreement anymore, and therefore any and all flight rights between the UK and the EU have to be renegotiated. But if KLM is really afraid of losing a hand full destinations or rather BA losing quite a few in each of 27 different states, is of course a different matter.