:salamext:
Guys, the issue isn't about consent before marriage.
Let me explain;
Usually, a marriage contract may take place - where there is an agreement between the guardian of the child, and the other person who will get married, that the marriage can take place. No consumation [sex] takes place etc. Also keep in mind that Aisha remained with her family until she became mature [at the age of 9], this is when she moved in with Allah's Messenger.
Then, when the child has reached puberty - they have the choice of going ahead with the marriage, i.e. consumation and the whole idea of marriage, or rejecting it. If they reject it [now that they're mentally, physically, emotionally mature] - the marriage can be cancelled/annulled.
If a girl isn't pleased with her marriage;
Al-Khansaa’ bint Khidaam complained to the Prophet that her father wanted her to marry someone she didn’t want, saying “I do not wish to accept what my father has arranged.” The Prophet said, “Then this marriage is INVALID, go and marry whomever you wish.” Al-Khansaa’ said, “I had actually accepted what my father has arranged, but I wanted women to know that fathers have no right in their daughter’s matters” (i.e. they have no right to force a marriage on them).
(Fath Al-Barî Ibn Hajr, Sunan Ibn Mâjah)
Why are these types of marriages permitted?
1) There's nothing which says this has to be done, its purely based on cultural practises. Usually due to joining families, strengthening relationships between different groups of people etc. Two tribes may be at war and may unite if there is a marriage between them to connect them together.
2) The guardian is responsible to give their offspring good people to marry, i.e. pious, someone of an equal position i.e. its recommended for a woman to marry someone who is of an equal status or higher status to her in societies eyes, so that she does not feel let down.
The guardian can't abuse this position, rather he is the guardian so he has to fulfill his duty. Not abuse this duty. He chooses her the best person he is able.
3) It's not always that the family is rich, a man may have 10 daughters and no sons. He may find it hard to provide for them, so he may marry his daughter to a good person, and that person may support the one he is married to financially, since she is his wife.
Without this aid, God knows what could happen [some societies may even send their daughters off to prostitution so the family can have the basic necessities of food, shelter etc.] Islam provides ways out of hard situations through the wisdom of Allah.
In regard to Aisha, its been explained before that Aisha was fit and mature and she knew herself well, more than any of us;
Imam Ibn kathir (May Allah have mercy on him) narrates a hadith in his Al-Bidayah wa-Nihayah:"Imam Bukhari (May Allah have mercy on him) narrates another hadith which he heard from Farwa bin abi al-Mughria who heard from 'Ali bin Masher who heard from Hisham bin 'Urawh who heard from his father who reports from
'Aisha (May Allah be pleased with her),
who said: 'When the Messenger of Allah (peace be upon him) was betrowth to me, I was six years old. Later, when we migrated from Makkah to Medina and satyed at bin harith bin khdhrj's place, I had grown up. My hair had got longer and
I had physically matured; however, I still used to play with other girls...
I was nine years old at that time."
Source Page 210-211
Just because people are brought up to be like teenagers or children throughout their lives in todays times, it doesn't mean that this was the case then or at other times in history. Usama ibn Zayd lead a whole battalion at the age of 16 to Syria/Sham during the death of Prophet Muhammad/early caliphate of Abu Bakr.
So without a doubt, people were way maturer and were brought up to be adults during their young adulthood. Their hot climate also enhanced their physical growth, and their ways of life did also.
So they weren't children, they were young adults.