The underlying problem here is that we are taught (by our culture) that: 1. It is okay to be subtly sexist but even worst, 2. We're being bitchy (uncool) if we defend ourselves (I'd argue that it's part of our intense worship of "being cool" but that's another topic)
I think we would be in a better position to tackle these problems of subtle sexism if it was more socially accepted (and encouraged) to stand up for yourselves (especially for females to stand up for themselves).
A side note: I read once that when asked, females would attack a rapist who is raping their friend or sibling but would not attack when they are themselves being raped by the rapist.
I think this stems from the theory 2 above: that we are viewed as bitchy if defend ourselves, but we are praised if we defend someone else.
Luckily, you were close friends. This makes things much easier. This lends weight to my worry about sticking up for other people when they show no signs of bother. Should I have been offended for Amy? I don't know her. As you pointed out, if I did, that would be just as sexist.
Let's be clear here, I'd probably feel uncomfortable for the person being denigrated in such a manner. But what is my responsibility?
I mention this because all to often people are quick to say "Hey, I'd jump in to defend a person," and while well meaning, it's just not that easy. Even women can't agree on this (not that they should). On one hand, Amy was perfectly content and these things didn't bother her. On the other hand, in some manner of speaking, they are still wrong. The move Shallow Hal comes to mind here (to some extent, as ignorance isn't the key part here).
This leads me to my way of thinking. Unless it's out right obvious and offends me, I'm not going to rush to the defense of someone because I think they should be offended. However, I will support people who do come out and clearly state they are offended, and support them. If they accept the treatment (for example, always taking notes at the meeting) without a word, who am I to treat them like a defenseless child incapable of defending themselves.
Supporting the person after they've made it clear they aren't happy with the mistreatment, on the other hand, I think is fair and proper.
Some people might feel awkward raising an alarm that something bothers them. This is understandable. In some manner, we must encourage them without outright saying "Hey, doesn't it bother you that you are always asked to take notes? (Maybe that's acceptable if the relationship is more than a co-worker type)."
In the end, it's the best I can offer.