FoM for people is a red herring here, given the CTA.
The problem is FoM of goods and services. Under WTO rules we cannot permit free movement of goods and services from the EU but not all other WTO members.
This is why if we leave the Customs Union there has to be a hard border between ourselves and the EU.
The Brexiteer position (as ably stated by ceptimus) is that the hard border requirement once the UK has left the customs union is all down to EU unreasonableness and intransigence. It's up to the EU to come up with a solution which will allow an open border between NI and Ireland, no internal border between NI and the rest of the UK and satisfy WTO requirements whilst allowing the UK to leave the customs union.
Honestly, I feel that Brexit is like moving house.
The referendum was something like "Do you want to move house ?" when we're living in a perfectly satisfactory suburban three-bedroom semi.
The "Move" campaign said that could have whatever kind of house we wanted and that the mortgage payments would be far lower. Indeed to some groups they said that we'd have a penthouse apartment in Mayfair, to others a beautiful seaside cottage and to others that we'd have a Scottish hunting estate. When the "Stay" campaign pointed out that these houses were mutually incompatible and that in any case they'd be far more expensive, and that moving would be an absolute nightmare, they were poo-pooed as being "Project Fear".
There was a tiny majority for moving and it suddenly has become clear that the process of selling up and moving to a new place is expensive and difficult (despite "Move" saying that selling our place and buying a new one would be super-easy) and that actually it's impossible to have a city centre penthouse with a grouse moor and seaside views and furthermore the best thing we can afford after all the sale and moving expenses is the same kind of house we have but in markedly worse condition.
Now "Move" have thrown their toys out of the pram and are railing against sellers (who refuse to sell us a city centre penthouse with a grouse moor and seaside views for our £350k budget),
Phil and Kirstie (for failing to find us a city centre penthouse with a grouse moor and seaside views for our £350k budget) and the members of the "Stay" campaign for failing to come up with some kind of solution.
Meanwhile we're pressing ahead with selling our current house despite not having a clue where we're moving to and being under no obligation to do so.
