I work in customer service and the level of stupidity I deal with daily is staggering. I am often surprised that some of our customers haven't drown themselves while drinking a glass of water.
Used to work in low-level IT back in the day. The number of times I've heard, "My laptop/computer/discman/et cetera isn't working, FIX IT," was staggering. The number of times my response was "You have to turn it on first," was in far greater numbers than you might think. Legitimately, without exaggeration, I can tell you that approximately 70% of all issues were related to the fact that these people simply
did not turn their devices on. Most of them turned red and got embarrassed, but enough of them were extremely angry with me, as though their lack of thought was my fault (though I recognized then and now that they felt dumb and just wanted to blame me). Left the industry about a year after college, when cell phones were becoming a popular thing, specifically because I knew that it was just going to create a new kind of dumb customer, and I'd had enough.
But yes, I've also experienced people trying to open the doors when we were closed, calling before or after posted hours, pushing on a pull door, and a whole bunch of other stuff. When I was freelancing as a writer/editor, price negotiations were fun, because I charged by the word. You would be stunned at the number of people violently angry that $0.05/word for 10,000 words is $500 and not $50, even after I had explicitly explained the math down to the middle school level (I drew one guy a sarcastic picture, with bunches of twenty words equaling a dollar, then adding groups until I hit the word count of the document, with each group clearly numbered; he still didn't get it).
As for Elaine, I don't think it's safe to assume stupidity where she's concerned. She lived with the Summer Fae for a long time, and while it's not as treacherous as Winter, I think assuming that survival requires quite a bit more savvy than you'd think. Look no further than her manipulations in Summer Knight, up to and including her false flight out of town,
knowing Harry would chase after her.