http://revach.net/article.php?id=4602

Section: Parshas HaShavua   Category: Quick Vort
Parshas Chukas: Rav Yehonoson Eibshitz - Only Tears But No Competition For Aharon's Job
"Vayivku Es Aharon Shloshim Yom Kol Bais Yisrael,"  (Chukas 20:29).  When Aharon died the Torah tells us that every single member of Bnei Yisrael cried.  However when Moshe died it only says that Bnei Yisrael in general cried but not every single person.  Why?

Rav Yehonoson Eibshitz answers that when Aharon died, Elazar, his son, was destined to fill his role.  No one had any ideas about inheriting his prestigious position.  Therefore, they all cried over his absence.  When Moshe was Niftar, he was succeeded by Yehoshua who was old and had no children.  That meant that the position would soon be vacant once again with no clear successor.  Some people, who felt they were legitimate candidates for the job, did not cry over Moshe's death, since their reward would outweigh the loss.