Most Greek City-States surrounded themselves with walls, but Sparta did not. Why didn't they need a wall?

Their life ideals were dedicated to fighting and defense, so they preferred to honorably defend the city with army and manpower rather than with the walls.

Explanation:

Sparta had a good geographical position – they were position in the Taygetos mountain rage that provided them with the natural protection which would slow down the enemy. Ready for the defense as they were, Spartans were on the watch way behind the edges of their city. With the mountains and guards ready, the enemy would hardly reach the borders of the city before being spotted and killed.

However, the biggest reason was the mentality and ethos of Sparta. Spartans valued the belligerence and were very talented fighters. They would train their armies from a very young age and be always ready for the fight. They preferred to have the manpower for defense instead of the walls. It was their point of pride and honor to fight and protect themselves and their city borders.

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.