This is really strange they did not allow you to trade. What laws were you breaking by bartering?
In the EU you can trade at will for free, without any government interference, even if you make profit. If I remember correctly there's a law in my country which states that used things that belong to you and weren't purchased with the intent to trade like books, tools, clothes, can be sold tax free. You can place ads online and sell them for fiat or cash. That's why people rarely trade. It's much easier to price things.
What the government might have been preventing was not the trade but the value that the people are trading are disregarded, they might be preventing hoarders that will try to amass quantities of items to sell at a higher price. Calling them tax evaders is a pretty bullshit notion. EU is a union of free countries so free market is a needed thing there, in some countries, corruption and free market is not the best interest for those in power so they do their best into cracking down on this kinds of people uniting together.