Tell me you don't see the value in the tax as a way of discouraging people from ordering a pair of socks from the other side of the globe, while they can buy them locally?

Why let a middleman rentseek?

This is global trade and comparative advantage at work. If someone outside the country can produce an equivalent product to what a local producer would make, they can supply it to our market more efficiently than our local producers, and there are no moral qualms (for example people working under conditions that are unacceptable by our standards) then everyone benefits from the import arrangement except for the local producers who can't compete.

From an economic perspective the local producer then needs to become more efficient and/or produce a better product to remain competitive. Alternatively they can do something else that is a more productive use of their time and skills. Again this is just a free market at work. The economic principle is no different if another local producer opened down the road from the existing local producer and they were the ones making the same product cheaper or a better product for the same price.

Protectionism arguably has a place. For vital interests like national defence there is an argument for making certain things locally so you have complete control because of the security implications and because the normal rules of international trade and diplomacy might not be working properly at the time when you need those products. But even in fields like defence and strategic infrastructure and perhaps the most obvious example of simply putting enough food on everyone's plate to survive there are few if any Western nations that don't rely significantly on international trade.

There is an example I always remember from the Brexit debates here in the UK. The Remain campaigners talked a lot about the advantages of being in the EU's Single Market and Customs Union. (These are the two big economic arrangements in the EU that allow member states to trade freely among themselves without tariffs or non-tariff barriers.) And certainly for intra-EU trade they do offer many economic advantages.

However the cost of being under the protectionist umbrella was much less discussed - surprisingly even by Leave campaigners. All member states are required to apply the common EU-based tariffs to anything coming into their country from outside the union. So when the EU introduced extremely high tariffs to protect the fruit growers in its Mediterranean member states that was good for those growers. But we don't exactly grow a lot of citrus fruit in the UK with our milder northern European climate. We also already had some established trade routes with north African nations that could supply similar products at potentially lower cost and would have liked to increase that trade with us - a mutual benefit for both their suppliers and our consumers that would have cost neither of us anything directly. The EU tariffs made that financially unviable and therefore benefitted some of the southern member states but at the expense of both consumers in the UK (also an EU member state at the time!) and the more efficient suppliers from Africa.

Protectionism is inherently inefficient economically. Sometimes it might be appropriate for other reasons but in purely financial terms it's almost always a negative effect.

Because we don't make those socks locally. They come from the other side of the globe.

For example, i want to buy a phone case... i can order one on aliexpress for ~1eur (free shipping) + 3eur tax + 88cents of vat and pay 4.88for it.

Or I can go to my local mall, and buy the identical case, made by the same chinese manufacturer for 12-15eur. The middleman can order 100 of those cases and since they're the same TARIC code, he'll still just pay 3eur (total) in customs for all of them (3% customs, instead of 300% if you order 1 piece only) and still be much more expensive than if I order directly from china.

So instead of paying 1eur + having 4 eur left over to go for a beer, i now pay almost 5eur, no local beer and 75% of that tax doesn't even go to my country but directly into EU budget. I can afford less and won't get anything out of that money. Yes, there's an employee in that cell phone store, but so is there an employee in my local bar where I can't afford beer anymore because EU took my money.