Obviously I have heard about things like this happening to the women in my life but it was until recently that I experienced something like that myself when I saw a guy jacking off at a bus stop a girl was sitting in. It was such a surreal experience to see that happening in broad daylight in a city and I was and still am shocked honestly.
I pushed the guy and asked him wtf he was doing and he fled on his bicycle before I could do anything further.
In my life I have never had to worry about a guy jacking off while waiting for my bus. Never. The closest I got to unwanted attention was women touching me in a club or something but that's it. If I was a women there would be no way that I'd leave the house without some kind of a weapon. That's just the sad reality. I literally know no woman that hasn't experienced something like you described.
I'm sorry you had to experience this. I hope the piece of shit wraps himself and his car around a tree soon.