Fluid borders make running a business in the EU so much easier becasue of the lack of stringent border contols.
After the Persian victories at Artemisium and Thermopylae, king Xerxes proceeded to Athens, which he captured in the last days of September 480. Meanwhile, the Greek navy, which had managed to get away from Artemisium, stayed on the isle of Salamis, opposite Athens. The presence of the enemy close to Phaleron, the Athenian harbor, created a strategic problem for the Persians: they could not use their port as easy as they wanted. And this was something they had to, because their army was proceeding to the Isthmus of Corinth, and it was imperative that the transport ships, brimful with food, could join the soldiers on the Isthmus. It was, therefore, imperative to expel the Greeks from Salamis.
laws that severely limited entry
Explanation:
Slavery, condition in which one human being was owned by another. ... a perceived labour shortage, for otherwise it is unlikely that most people would bother to acquire or to keep slaves.
Because a lot of people were not subject to it and so they werent taxed
