The aim to have single market access totally different to being part of it as you have to abide by EU rules, countries like USA, China have this access to it now Canada without the four freedoms - we only originally voted for trade imo let's get back to that deal - working visas is not a great deal from all over the world to trade with, and deal with worldwide countries its a no brainer - it happened before 1974 !
Trade agreements aren't just tariff agreements though Joe. They're increasingly a whole lot more than that, and involve everything from environmental standards to IP protection. Take driverless cars as an example. Sure, there may be negotiations around tariff free trade of such vehicles, but there will be way more to ensure that cars that work in one country work just as well in others, that they're regulated in the same way, that mapping data meshes effectively and all manner of other things.
So this idea that we can somehow trade internationally without cooperating with other nations/bodies on these things (and thus being 'governed' by external bodies) is not true in the modern world.