Alma 20

We learn of Aaron had his brethren that -

"...it was their lot to have fallen into the hands of a more hardened and a more stiffnecked people; therefore they would not hearken unto their words, and they had cast them out, and had smitten them, and had driven them from house to house, and from place to place, even until they had arrived in the land of Middoni; and there they were taken and cast into prison, and bound with strong cords, and kept in prison for many days..."  (Alma 20:30)

Mormon makes it clear with "it war their lot" that just because our missionary experiences are not the same, some with success and others unsuccessful, it does not reflect on ones righteousness or favoritism.