You realize the original translation dosen't use the word rape. it simply states that if a man has sex with a woman who is a virgin, he must marry her. In fact none of the traslations even use the word rape. Did you forge that into the verse??
22:28-29 Preceding legislation dealt with cases of rape involving a woman already married or engaged.
The ruling outlined here is addressed in cases of seduction IN WHICH IT IS ASSUMED THAT THE WOMAN WAS, OR MAY HAVE BEEN, CONSENTING TO THE SEXUAL RELATIONSHIP. The fact that such a relationship had taken place was nevertheless regarded as of vital concern to the community and therefore required that a requisite sum of money be paid to the woman's father. It is assumed that the bride's father's rights have been violated by what had taken place and that appropriate compensation was necessary to offset the loss of the expected bride-price. A further stipulation required that the couple should then marry and that no subsequent divorce was to be permitted. In Exodus 22:16-17 the closely comparable law allows that the father need not consent to giving his daughter to the man, in which case the compensation was still to be paid to the father.
Fifty shekels was a significantly large amount and may be assumed to have been equivalent to the average bride-price.
http://www.answeringislam.info/Shamoun/ot_and_rape.htm
"If a man entices (pathah) a virgin who is not betrothed, and lies (shakab) with her, he shall surely pay the bride-price for her to be his wife. If her father utterly refuses to give her to him, he shall pay money according to the bride-price of virgins." Exodus 22:16-17
Note that in this passage the word
pathah is used in place of
taphas