Under Islamic law, why is a woman’s share of the inherited wealth only half that of a man?

Inheritance in the Qur’an
The Glorious Qur’an contains specific and detailed guidance regarding the division of inherited wealth among the rightful beneficiaries. The Qur’anic verses that contain guidance regarding inheritance are :

1-Surah Baqarah, chapter 2, verse 180

2-Surah Baqarah, chapter 2, verse 240

3-Surah Nisa, chapter 4, verses 7-9

4-Surah Nisa, chapter 4, verse 19

5-Surah Nisa, chapter 4, verse 33

6-Surah Maidah, chapter 5, verses 106-108

Specific Share of Inheritance for the Relatives
There are three verses in the Qur’an that broadly describe the share of close relatives, i.e., Surah Nisa, chapter 4, verses 11, 12, and 176. The translations of these verses are as follows:
“Allah (thus) directs you as regards your children’s (inheritance): to the male,
a portion equal to that of two females; if only daughters, two or more, their share is two- thirds of the inheritance; if only one, her share is a half.

For parents, a sixth share of the inheritance to each, if the deceased left children; if no children, and the parents are the (only) heirs, the mother has a third; if the deceased left brothers (or sisters), the mother has a sixth.
(The distribution in all cases is) after the payment of legacies and debts. Ye know not whether your parents or your children are nearest to you in benefit. These are settled portions ordained by Allah; and Allah is All-Knowing, All-Wise.”
[Al-Qur’an 4:11-12]

“They ask thee for a legal decision. Say: Allah directs (them) about those who leave no descendants or ascendants as heirs. If it is a man that dies, leaving a sister but no child, she shall have half the inheritance.
If (such a deceased was) a woman who left no child, her brother takes her inheritance. If there are two sisters, they shall have two-thirds of the inheritance (between them). If there are brothers and sisters, (they share), the male having twice the share of the female.
Thus doth Allah (swt) make clear to you (His knowledge of all things).”
[Al-Qur’an 4:176]

Female Sometimes Inherits Same or More Than Male Counterpart
In most cases, a woman inherits half of what her male counterpart inherits. However, this is not always the case. If the deceased has left no ascendant or descendant but has left uterine brothers and sisters, each of the two inherits one-sixth.
If the deceased has left children, both parents (i.e., mother and father) get an equal share and inherit one-sixth each. In certain cases, a woman can also inherit a share that is double that of the male.
If the deceased is a woman who has left no children, brothers, or sisters and is survived only by her husband, mother, and father, the husband inherits half the property while the mother inherits one-third and the father the remaining one-sixth. In this particular case, the mother inherits a share that is double that of the father.

Female Usually Inherits Half the Share of That of the Male Counterpart
It is true that as a general rule, in most cases, the female inherits a share that is half that of the male. For instance, in the following cases :

1-The daughter inherits half of what the son inherits.

2-The wife inherits 1/8th and the husband 1/4th if the deceased has no children.

3-The wife inherits 1/4th and the husband 1/2 if the deceased has children.

4-If the deceased has no ascendant or descendant, the sister inherits a share that is half that of the brother.

Male Inherits Double Than the Female Because He Financially Supports the Family
In Islam, a woman has no financial obligation, and the economic responsibility lies on the shoulders of the man.
Before a woman is married, it is the duty of the father or brother to look after her lodging, boarding, clothing, and other financial requirements.
After she is married, it is the duty of the husband or son. Islam holds the man financially responsible for fulfilling the needs of his family.

In order to fulfill this responsibility, men receive double the share of the inheritance. For example, if a man dies leaving about Rs. 150,000 for the children (i.e., one son and one daughter), the son inherits Rs. 100,000 and the daughter only Rs. 50,000. Out of the Rs. 100,000 which the son inherits, as his duty towards his family, he may have to spend almost the entire amount (say about Rs. 80,000), leaving him with a small percentage of inheritance, say about Rs. 20,000.

On the other hand, the daughter, who inherits Rs. 50,000, is not bound to spend a single penny on anybody. She can keep the entire amount for herself. Would you prefer inheriting Rs. 100,000 and spending Rs. 80,000 from it, or inheriting Rs. 50,000 and having the entire amount to yourself?