Thankfully most of them are that stupid. For me its called job security.
I always wonder about that; it seems that criminals are unbelievably stupid, but I guess if they weren’t unbelievably stupid, they wouldn’t be getting caught (or doing stupid crimes in the first place).
I’m not thinking stupid. I’m thinking crazy, and the young lady in the OP, by her size, standing very near the door, and apparent aloneness, made it easy for a deranged person to grab her as a target of opportunity. It doesn’t happen often, probably because you need insanity and naivety to intersect in the right conditions, but it is a situation women should be trained to avoid.
You, OTOH, seem to be situationally aware and carry a 'tude like a weapon. You are likely too scary to attract any but the very craziest crazy stranger.
ETA: And her stone sexy parka could drive many a man to sexual violence. Was it down filled? Did it make her look like the Michelin Man? Because that is a hot look.
Seems women are gonna get shit, no matter what they do.
I do a lot of walking. I will walk through the shittiest alley when my gut tells me its okay to do. My experiences have equipped me with a set of habits and tendencies, both conscious and unconscious, that give me a sense of security. They may actually keep me safe, I don’t know.
A guy that catches me walking on a regular basis is always telling me I need to smile more and not look so “mean”.
That “mean” face? It’s my way of keeping the freaks like him away from me.
Nope. I don’t walk around in fear for my safety, so I don’t go around carrying weapons.
Haven’t been violently attacked once.
Ah, but a bad-assed attitude is a part of you and needn’t be put on like a holster.
There’s nothing at all scary and intimidating about you.
Granted, she’s got a mean arm when it comes to weaponized Monchichis. But otherwise, she’s a very laid-back person. No 'tude at all.
So you’re the older sister, eh?
She is. By one minute.
The smart ones do credit card fraud. Low risk, high reward.
So she’s the Evil Twin. Funny how early that manifests itself. We figured out which of ours was the Evil Twin before they were one.
Now, now. Serial killer Jerry Brudos murdered a female encyclopedia salesperson who knocked on his door, so the scenario The Great Sun Jester finds plausible has actually happened. Once. Forty-five years ago. So obviously it is very foolish for any woman to knock on any door, ever.
Then I’m glad we agree. Mind you I don’t know whether you’ve really considered the advantages of owning a really fine set of modern encyclopaedias… 
Actually, serials are not the problem. They are outliers of outliers, and very rare. My concern is with your friendly, neighborhood psycho getting a crazy idea in his head. Those guys aren’t rare enough. I blame Ronald Reagan for emptying the mental hospitals to save money by “mainstreaming” mental patients without actually providing them with the care they needed, but I should probably find a more recent bête noire.
How do you know they weren’t working in pairs? but instead maybe taking one driveway each? Or one side of the street? With an update after every house?
It seems to me - not being allowed to knock on a door at 7pm places undue restrictions on ladies.