In addition to other answers: How is prostitution different?
Such women aren't women of the street, they are socially acceptable women.
Having said this all I would tell you among Shias, 70 of them do Sighe/Muta'ah just prior to their permanent marriage (only as a fiance period).
It was narrated from al-Rabee ibn Sabrah al-Juhani that his father told him that he was with the Messenger of Allaah (peace and blessings of Allaah be upon him) who said, O people, I used to allow you to engage in mutah marriages, but now.In the same manner, the Prophet (peace and blessings be upon him) adopted a gradual course in the matter of sex.Almighty Allah says: And Allah has brothels in hartlepool made for you spouses of your own nature, and from your spouses has made for you sons and grandsons.Moreover in the case of Mutah the children born of such union were to be subject to social disability which was detrimental to social order.With it it's considered Halal and rewarding.Masud and others that the Messenger of Allah (peace be upon him) prohibited Mutah marriage (temporary marriage for a stipulated period so it was settled in Shariah (Islamic law) that it is prohibited and that Shary (Islamically lawful) marriage is one in which a man.They are refugees who fled from their war-torn countries.Thereupon Hudhaifa divorced his Christian wife.Temporary marriage is in which a man and a woman agree to marry for a fixed period of time.This gives the bride and groom a good chance to see if they are a good match and if needed divorce early.Prostitution isn't accepted in the realm of our King, Allah.In your comments I see you said: Hardly, its just like saying Mutaa is different from prostitution because its considered to be legal "among Muslims".
A person asked him about marrying women on a haram basis, and he permitted him to.
If any person marries the idea is to establish a home.

Displaced sufferers of human trafficking.Set Upon being critiqued by Umman bin Sawad for his decision, Umar (r) explained why he prohibited Mutah : About the Mutah, Umar said: Mutah was an ancient practice with the Arabs.Culturally it's not a common thing to do these days.In his realm sayings those words (with the 100 intention of your heart that you approve and mean them) is what makes Allah accept.He was asked about what kind of women are good to do Mutah with?Prostitution is a way of making money.Mutah is meant as a solution for younger boys and girls.Umar took cognisance of this unsocial practice.In addition men have been given a great touchstone by Imam Ja'far al-Sadiq.It's more about fulfilling needs.They have a choice between leaving their small children at home alone or bringing them along when they have sex with men.

Mutah there is an agreement and a timeframe specified.
She has modesty but also wants to have a joyful time with a man).