I've been slowly trying to excise sexist terms from my own language over the years and while yes, it's really, really hard - "bitch" especially is almost impossible to get around - it's doable, particularly in writing when you have a chance to catch yourself, re-evaluate, and change what you've put down.
I've been trying to do the same, if probably not for as long as you have, and I've run into the same wall. I think that there are two conflated reasons. The first reason is that it has taken on a couple of meanings beyond the technical one. The second is that few people really think about what they're saying when they say it because it is so common.
Hmm. There are certainly more offensive sexist insults, but none of those are ever tossed out casually. I wonder if that might make it the worst of all.
Also, I cut the conversation in the invisible plane on the way to Sebastian's hideout, in which all three of them gush about their respective male crushes in the most awe-inspiring violation of Bechdel's I think I've ever seen.
*blinks*
They were talking about what on the way to where?
That's just--- GAH!
*sigh*
I can picture the Flashes talking about relationships on their way to fight a villain, because every single one of them is devoted to a special someone. The GL's might do it too, although that conversation would have a very different feel. However, the only family group that has anything like the warrior focus of the Wonders is the Batclan, and I cannot imagine any writer having Batman, Nightwing, and Robin talking about women on the way to fight the Joker. Having them mentally angst about Barbara and maybe Sarah is one thing, but they wouldn't actually be talking. Talking about women might have a deleterious effect on Bruce's double-standard, and we can't have that.