In an article for Mikeitz, 5773, Rabbi Cherki explains why the Egyptians could not understand Pharaoh's dreams and only Joseph could.
It took Pharaoh two years until he had a dream. From the book of Genesis, which is so full of dreams, it is clear that the dreams in the Torah are not simple nighttime visions but have something of the traits of a prophecy. They appear within the family of the Hebrews as a unique skill that can be transferred to other people who are close to them. Abimelech has a dream when Abraham and Sarah appear in his kingdom. Josef, the dreamer, causes the people in his prison to dream. And when one of them, the Minister of Cupbearers, moves over to the house of Pharaoh, the king has a dream too.
The interpretation of Pharaoh's dream is so simple that it is difficult to understand why the wise men and sorcerers of Egypt could not explain it, so much so that when Yosef gave the explanation he was told, "after G-d has told you all of this, nobody is more understanding and wiser than you are" [Genesis 41:39]. Every child could be expected to understand that the fact that the cows and the crops are fat at first and then become lean means that at first there will be a lot of food and that this will be followed by a lack of food. And the idea that seven refers to a number of years is related to the fact that the same word is used for "cow" and "year" in the Egyptian language.
The answer to this question is that if we understand ancient Egypt we can see why they could not figure out the meaning of the dream. In order for a famine to occur in Egypt, it was necessary for the Nile River to stop fulfilling its normal task, something that was unthinkable, since the Nile was a deity in their eyes. The gods in Egypt were the natural forces, which were approached in a deeply religious fashion. This meant that natural forces and all natural determinism became absolute values. Egypt was a mental "House of Slaves" in every way, since nothing in the land could ever change. Everybody was a slave: the slaves belonged to their masters, the masters were slaves of Pharaoh, Pharaoh was a slave of the gods, and the gods were slaves of nature. Any thought of change was heterodox and simply impossible.
How, then, was Pharaoh able to dream about change? It is because he was on the way to become a Hebrew. That is why he was able to deviate from the ideology forced on him by the Egyptian culture and to have this rare opportunity to bring the influence of Abraham in its midst. Pharaoh was sensitive to the language of Josef, and he therefore put him at the top of the pyramid in Egypt (pun intended).
This unique occurrence of cooperation between the Hebrew culture and the general culture led Yosef to think that he would be able to bring the children of Rachel to Egypt and take Benjamin on as a partner, separating themselves from the children of Leah. That is the explanation of the affair of Josef's goblet, which was meant to completely sever Benjamin from his brothers so that they would agree to leave him behind in Egypt as a slave. But this took place before Josef understood that he was really striving with all his might to complete the process of repentance by his brothers. In the end, it would lead to Judah displaying his willingness to sacrifice himself for Benjamin and to the development of the mutual responsibility among the Jews, and it would prevent a division within the nation.
Source: "AS SHABBAT APPROACHES" – a biweekly column in Shabbat B'Shabbato, Mikeitz 5773, Volume 1453. (Zomet Institute) See:www.zomet.org.il/eng