Praise be to Allah.
There are many fatwas from scholars which say that it is forbidden for a driver to be alone with a non-mahram woman, because of the text which states that it is haraam to be alone with a non-mahram woman, and because of the obvious evil consequences to which that may lead, whether one is going to a center for memorizing Qur’aan or to a mosque, so the prohibition is even stronger when going to the marketplace etc. This ruling has to do – as mentioned in the question – with the first female passenger in the morning and the last female passenger in the afternoon. In order to avoid any problem, there should be two female passengers who get on together first in the morning, and two who get off together last in the afternoon. There follow some of the fatwas of the scholars:
Shaykh Muhammad ibn Ibraaheem (may Allaah have mercy on him) said:
There can be no doubt that if a non-mahram woman travels with a driver without a mahram to accompany her, this is obviously wrong and involves a number of evils which are not insignificant. The man who approves of this for his mahrams (female relatives) is lacking in religious commitment and manhood, and he has little protective jealousy (gheerah) towards his mahrams. The Prophet (peace and blessings of Allaah be upon him) said, “No man is alone with a non-mahram woman but the Shaytaan is the third one present.” (Narrated by al-Tirmidhi, 2165; classed as saheeh by al-Albaani, 1758). For her to ride with him in a car is more serious than being alone with him in a house etc, because he can take her wherever he wants in the city or outside the city, whether she agrees to that or goes unwillingly, and there may result from that evils far worse than simply being alone with her.
The fitnah (temptation) posed by women and the evil things that result from that are well known. According to the hadeeth, “I have not left behind me any fitnah more harmful for men than women.” (Narrated by al-Bukhaari, 5096; Muslim, 2740). According to another hadeeth: “Beware of this world and beware of women, for the first fitnah of the Children of Israel was because of women.” (Narrated by Muslim, 2742)
Because of this and other similar reports, and because of what is in the public interest and what is required of us by our religion, we think that we should definite in not allowing any non-mahram woman to ride with a taxi driver unless she is accompanied by one of her mahrams or people who could take the place of a mahram or a trustworthy person who is connected to her mahram.
Fataawa al-Mar’ah al-Muslimah, 2/553, 554
Shaykh ‘Abd al-‘Azeez ibn Baaz (may Allaah have mercy on him)
It is not permissible for a woman to travel with a driver who is not her mahram when there is no one else with them, because this comes under the ruling on khulwah (being alone with a member of the opposite sex). It was narrated that the Messenger of Allaah (peace and blessings of Allaah be upon him) said: “No man should be alone with a (non-mahram) woman unless her mahram is also present.” (Narrated by al-Bukhaari, 5233; Muslim, 1341). The Prophet (peace and blessings of Allaah be upon him) said: “No man should ever be alone with a non-mahram woman because the Shaytaan will be the third one present.”
But if there is one or more other men present, or one or more other women, then there is nothing wrong with that, because there is nothing dubious in this case, since there is no khulwah when there are three or more people present.
This has to do with situations that are not regarded as travelling [i.e., journeys within one’s city or town etc]. With regard to travelling, it is not permissible for a woman to travel without a mahram, because the Prophet (peace and blessings of Allaah be upon him) said: “No woman should travel without a mahram.” (Saheeh – agreed upon).
It makes no difference whether the travel is by land, by air or by sea. And Allaah is the Source of strength.
Fataawa al-Mar’ah al-Muslimah, 2/556
Shaykh Muhammad ibn Saalih al-‘Uthaymeen said:
It is not permissible for a man to be alone with a woman in a car unless he is her mahram, because the Prophet (peace and blessings of Allaah be upon him) said: “No man should be alone with a (non-mahram) woman unless her mahram is also present.”
But if there are two or more women with him, that is o.k., because there is no khulwah in this case, so long as he is trustworthy and they are not travelling. And Allaah is the Source of strength.
Fataawa al-Mar’ah al-Muslimah, 2/554, 555
Shaykh Saalih al-Fawzaan (may Allaah preserve him) said:
It is not permissible for a woman to travel in a car on her own with a driver who is not her mahram, whether she is going to the mosque or anywhere else, because of the stern prohibition against a man being alone with a woman whom he is not permitted to be with.
But if there is a group of women with the driver, then the matter is less serious, because this is not the khulwah which is forbidden. But they must observe proper etiquette and modesty, and not joke or chat with the driver, because Allaah says (interpretation of the meaning):
“then be not soft in speech, lest he in whose heart is a disease (of hypocrisy, or evil desire for adultery) should be moved with desire, but speak in an honourable manner”
Fataawa al-Mar’ah al-Muslimah, 2/556, 557
And Allaah knows best.