Amazingly, after everything that happened with Brexit, and the economic downsides it has now clearly be shown to have, Switzerland is currently going through a similar process. Of course, they never were EU members, but they had large collection of agreements that resulted in a very profitable and practical relationship wtih the EU. (Practical, because the economies and labour markets of Switzerland's border area are deeply integrated with those of the EU regions right across those borders, and breaking that up will pose huge challenges.)
Talks have been going on for seven years to wrap that patchwork of agreements into a large and more dynamic agreement that doesn't need renewal and updating every other year, but driven by a deeply nationalist government, Switzerland has been stalling the negotiations and now has just simply walked away from them. This is the same party (SVP) that some years ago pushed for a referendum on limits (or was it an outright ban?) on foreign workers in Switzerland.
And so now, those existing agreements will slowly disappear as they expire one after the other, and Switzerland will be free! Of those pesky foreigners? Cause as I said, they were never a EU member in the first place. Nationalists eh - all only for the good of the country!
To maybe find some middle ground here: it is absolutely true that the EU is very protectionist about its economy, and that this is very damaging to developing economies. I was reading an article about Tunesian olives a couple of months ago, that are apparently of very high quality, but can't make their way into the EU through proper channels that would bring the right money to Tunesia, simply because the EU is protecting its own olive industry.
I can understand why countries want to protect some of their industries, especially for crucial products (like food). But on the other hand, if you want to be serious about supporting developing economies, then fairness in trade would be an excellent starting point. I do agree with
@4bars, though, that environmental, health, and labour regulations need to be in place; otherwise 'fairness' just means 'race to the bottom', and that doesn't help anyone.