Why are spider webs a popular christmas decoration in poland

The answer is because in Poland it is believed that a spider wove a blanket for baby Jesus.

Explanation:

Spiders are a symbol of goodness and prosperity during Christmas in Poland. It is common to see spider webs and spiders as Christmas tree decorations in Poland. It is also a very common folktale in the Western Ukraine. Apparently it is also believed this folk tale explains the origin of tinsel on Christmas trees, which is more common to Britain and American households as decorations for the Christmas tree.  Finding a spider in a Christmas tree is considered good luck in Eastern Europe and so is finding a real spider's web.

trade regulation is a field of law, often bracketed with antitrust (as in the phrase “antitrust and trade regulation law”), including government regulation of unfair methods of competition and unfair or deceptive business acts or practices. antitrust law is often considered a subset of trade regulation law. franchise and distribution law, consumer protection law, and advertising law are sometimes considered parts of trade regulation law.

in general the theory of economics says that the more open to trade a country is the better   the result for the same country and the whole economies.

in real life countries impose taxes, quotas, etc which is not so good for the economies.

this kind of commercial war between the usa and china is slowing down the growth of the whole world so we can say that it is a draw back of trade regulations. and the free trade agreements are benefits of trade regulations.