I think people notice people in heels, it is just that they just act like they don’t notice.
I see it with my wife wearing high heels quite often, but honestly, I am situationally aware to a fault. For instance, I always sit in the back of the restaurant and face the front door, always have a second means of escape, judge people for nefarious intent as they come in and out, and of course carry a concealed firearm. Yep; I am situationally aware to a fault.
But I see guys checking out my wife a lot, and these are looks that my wife never sees. She is too engrossed in not tripping to really notice what is going on around her. And while guys want to look, the last thing they want is her husband (me) knowing they are looking so they hide how they look. I would never fault them; my wife and I are almost always well dressed when outside our home so it garnishes attention. And part of that is high heels becoming less common to see so it is noticed more when they are worn.
On my own front, I notice what people wear. In fact, in men and women’s fashion it is said to buy the best shoes that you can afford because it is the first thing people note about you, and the longest lasting impression fashion wise. I like high heels and know which women at our church tend to wear them and watch for them as they arrive. I am always discreet and not creepy about it, but I notice, and I do not think I am alone in that. So I truly think most people notice, its just they don’t act as if they do.