Thunder Bolt
Silly old bat
FoM is not a founding principle of the EU. It is a founding principle of the single market, alongside the other three freedoms - movement of capital, services & goods - which no-one in the UK ever mentions because, as one of the "big old" EU members, they suit us just fine.
It took the better part of a decade to create the single market. Millions of person-hours in meeting rooms, thrashing out the ball-achingly dull minutiae of it all. But guess what? It actually works. Frictionless trade between more than two dozen countries that have spent much of the last two millennia invading, fighting or subjugating each other instead. This is why they weren't bluffing when they said, before, during and for more than two years after the referendum, that the four freedoms are indivisible. Take away any one of the freedoms and the single market is not a single market any more. It is not going to happen - not for any of the 27, and most certainly not for a former *EU* member that wants to leave.
You can be a member of the EU. Or not. You can also be a member of the single market. Or not. But if you want to be a member of the single market, you must - fairly reasonably, imo - abide by its rules, regardless of whether you are in the EU or not.
And while leaving the EU is just very, very stupid (again, imo), leaving the single market is, by any objective analysis of the actual numbers, f***ing insane.
I wish I could give you more than one thumbs up for an excellent post.