Because women are taught to be agreeable and non-confrontational and non-argumentative. We smile, we nod, we say “Oh, I’m sorry!” for unnecessary reasons. We’re taught to worry about what others think of us, instead of learning that someone’s else’s opinion is just that, an opinion, and not a statement of fact that we must reshape our lives to. And it makes us look like pushovers.
I notice when certain types of men wish to feel better, they take out their ish on women. You don’t have to be one of those women. This dude may have been having a bad day, and whether he was or not, or whether he’s just a bully and a jerk, you needn’t take anything he said seriously. Yes, I know people do this to each other in general, and the same thing applies.
This isn’t to say you should engage ignorant strangers by telling them off if they aren’t threatening you.. But the very fact that you’ve realized that smiling and nodding isn’t the best response is a good step. It’s OK to not even respond in any way to such idiocy. Feel free to carry yourself forthrightly in the world with your dog and guys like that will pick up on it and not open their mouths.