I just got done discussing this issue with some non-Greeks who were trying to tell me that the brothel law was sexist. First I had to explain to them that the brothel law does not exist . . . then they claimed that it was STILL sexist if sororities were petitioning for housing and getting denied -- so I had to explain the difference between NIC and NPC policies, among other things. Needless to say I think I confused them.
I think that sexism played a role in the past but has less of a role in the present. Mostly I think it's those crazy commie NPC policies
stating that if the groups get housing, it generally has to be equal -- if even one of the groups on campus can't afford a house, it's tough for the rest of them to be approved. Also, on many campuses (especially that didn't open themselves up to women, or to sororities, until later in their history), all the appropriately zoned land had been used up by the time sororities came onto campus, or petitioned for housing. That's why I think past sexism plays more of a role than present sexism -- I don't think the sororities would be denied houses if there was still land available for it.
As for housemothers -- I think most sororities still have them, whereas the majority of fraternities do not. They aren't as involved as they once might have been, but they still play a role. As for manners -- to a certain extent our housemom still enforces the "gracious living" aspect of living in the sorority house -- at dinner we all stand until she sits down, ask her if we can be excused after dinner, etc. Most of the time she is out of our way, though, and I think that might be the norm for chapter houses these days.