Things I Don't Understand

 I don't know why women aren't more into frottage.  I mean, if I'm rubbing my dick against your ass on a crowded train, it's another way of saying  you are standing in front of me and can't move  I find you attractive.  Shouldn't they feel good about such a compliment?  It's just a more immediate version of writing a poem, or sending flowers, isn't it?  I don't don't understand the social taboo to this one.