What is the use of the passive conjugation in these sentences?

Question

I stumbled upon this sentence:

多くの方々が命を奪われた。

While I understand what this means, I'm not sure of why the passive verb there is (supposedly) correct. If I were to say that, I'd say

多くの方々の命が奪われた。

Since it's a passive verb, shouldn't 命 be the subject of the sentence?

Answer 1

Well the meaning is slightly different.

多くの方々が命を奪われた

Many people have had their lives taken.

多くの方々の命が奪われた

Many people's lives have been taken.

Look at where the が is attached to and it shows where the focus of the sentence is. In the first, the focus is on the people. In the second, the focus is on their lives. To answer your question of "shouldn't it be," it's a case of what the writer / speaker wants to focus on.

It's worth it to note the difference in usage has a slight nuance difference as well, I think. PersonはXをされた usually expresses more of a negative feeling than simply saying PersonのXがされた because if the person is the subject then there's more impact that it happened to a person and not an object.

Answer 2

Both sentences are correct and mean almost the same thing.

• 多くの人々が（津波に）命を奪われた。
  = Many people were robbed of their lives (by the tsunami).
  = Many people had their lives taken (by the tsunami).
• 多くの人々の命が（津波に）奪われた。
  = The lives of many people were taken/lost (by the tsunami).

The first form, where the person itself is the subject, is sometimes called 迷惑の受け身 (passive of inconvenience). See this article, this one and this answer.