Here is an example of an early Jewish Ketubah
(From JewishEncyclopedia.com)
A marriage contract, containing among other things the settlement on the wife of a certain amount payable at her husband's death or on her being divorced. This institution was established by the Rabbis in order to put a check on freedom of divorce, to obtain which no consent is required on the part of the woman (
see Divorce).
Some of the rabbis considered the ketubah of a virgin to be of Mosaic origin (Yeb. 89a; Ket. 10a; Tos.
s.v. "Amar"; comp. Tobit vii. 14).
Form of Ketubah.
"On . . . [day of the week], the . . . day of the month . . . in the year . . . since the creation of the world, the era according to which we are accustomed to reckon here in the city of . . . how . . . son of . . . said to this virgin . . . daughter of . . . '
Be thou my wife according to the law of Moses and Israel, and I will work for thee, honor, support, and maintain thee
in accordance with the custom of Jewish husbands who work for their wives, honor, support, and maintain them in truth. And I will set aside for thee 200 zuz, in lieu of thy virginity, which belong to thee (
according to the law of Moses), and thy food, clothing, and necessaries, and live with thee in conjugal relations according to universal custom.' And . . . this virgin consented and became his wife. The dowry that she brought from her father's house, in silver, gold, valuables, dresses, and bedclothes, amounts to . . . [100 silver pieces], and . . . the bridegroom consented to increase this amount from his own property with the sum of . . . [100 silver pieces], making in all . . . [200 silver pieces]. And thus said . . . the bridegroom, 'I take upon myself and my heirs after me the responsibility of this marriage contract, of the dowry, and of the additional sum, so that all this shall be paid from the best part of my property, real and personal, that I now possess or may hereafter acquire. All my property, even the mantle on my shoulders, shall be mortgaged for the security of this contract and of the dowry and of the addition made thereto.' . . . the bridegroom has taken upon himself the responsibility for all the obligations of this ketubah,
as is customary with other ketubot made for the daughters of Israel in accordance with the institution of our sages—may their memory be for a blessing! It is not to be regarded as an illusory obligation or as a mere form of document. We have followed the legal formality of symbolical delivery ["ḳinyan"] between . . . son of. . . , the bridegroom, and . . . daughter of . . . , this virgin, and have employed an instrument legally fit for the purpose to strengthen all that is stated above, and everything is valid and established.
In his book, The Jewish Marriage Contract, by Louis M Epstein, (linked to earlier) He states that "the tradition [that a ketubah-less marriage represents concubinage] must be as old as the ketubah itself and its origin is probably Babylonian, for Hammurabi (2200 BC this is pre Abraham) rules in his code, "
If a man take a wife and do not arrange with her the proper contracts, that woman is not a legal wife." (Emphasis mine)
The indentured wife has more protections because she's more at risk which makes perfect sense when you are familiar with who God is.
All that Moses is doing is giving an indentured woman who has been consummated with, the same foundational rights as a woman wed with a contract enumerating those foundational rights. The husband cannot disregard her natural rights just because she is without a contract. If he has humbled her, these are her rights, contract or no.
This truly shows that God is no respecter of persons.
The indentured wife without contractually enumerated rights
is given as much protection with the same basic foundational rights as every other free-born wife.
I cant explain why God doesn't choose to give us a detailed account of the wedding contract (which was apparently common some 700 years pre Moses), but apparently something like this was in use commonly, and our only point of reference to it biblically is when Moses gives a woman without legal recourse, the same legal rights as a "legal" wife.