In Parshat Dvarim (Dvarim 1:22-25), we read about the process that Moshe went through in sending the scouts:

All of you approached me and said: “Let us send men ahead of us and let them spy out the Land and bring word back to us: the road on which we should ascend and the cities to which we should come.” The idea pleased me, so I took from you twelve men, one man per tribe. They turned and went uphill and arrived at Nachal Eshkol, and they spied it out. They took in their hand some fruit of the land and brought it down to us. They brought back word to us and said, “Good is the Land that HaShem, our God, is giving us.”

Why did Moshe have to say “I took from you twelve men” rather than “I took” or “I sent”?

The Netziv, Rabbi Natali Zvi Yehuda Berlin in his commentary Ha’amek Davar answers:

Since the stated goal was to see how to conquer the Land, it would have been better to hire non-Jewish spies like members of the “Erev Rav,” the mixed multitude (Egyptians and members of other nations who left Egypt with B’nai Yisrael at the time of the Exodus), who were experts in war and conquest. In addition, such people would have been less apprehensive about traveling through the Land, and would not have been recognized as agents of the Jews.

However, Moshe Rabbeinu knew that by the laws of nature, it would be difficult to conquer the Land without strong faith and trust in God along with a desire to inherit the good Land. None of this could have been done by foreigners, only “from you”, because Jewish scouts would see the pleasantness of the Land and its special fruit. This way, the Land would find favor in the eyes of her children.

Moshe also thought that that scouts would become strengthened like Kalev when he entered Chevron. They would have felt confident that they could conquer the Land. Had all of the scouts done so, it would have greatly enhanced their trust in God as well as Israel’s fortitude. This could not have been accomplished through foreigners, who see only the physical walls and the people inside.

We see from here that checking out the Land was not a job that could be outsourced. There was an element of spirituality to the mission to help the people feel closer to God and the Land of Israel that needed to be accomplished by Jewish scouts.

Unfortunately, aside from Yehoshua and Kalev, the rest of the scouts did not feel enough of a connection with God or the Land and we see in Parsha Shlach that they even tried to scare B’nai Yisrael off from entering the Land.

Although sending Jewish scouts was important, it wasn’t enough to make the mission successful. It takes more than just being Jewish to be the right candidate for the job.