Or if they do use it, they don't do so in such a way that the signal actually communicates anything.
The way I get out of my neighborhood is by turning left onto a busy two-lane road with a speed limit of 45. I can't tell you the number of times I've watched as a long string of cars advances from the left, only to have the front car signal, oh, twenty feet before the turn. I would have had plenty of time to head out had I known they would be slowing down.
And then there are the tricky merges onto and off of Highway One, where the far right lane both continues on (is essentially a frontage road) and feeds traffic onto the highway. How many times have I almost been sideswiped because someone merging didn't bother to signal?
If you signal, I will give you room! If you don't, I assume you're going straight! No, I cannot read your mind!
Is that so complicated?
I once got pulled over in Italy after I'd merged onto the autostrada: two police officers in the middle of the highway waved a little red sign at me, signaling me to stop. My Italian is not good, but it was good enough for me to understand that I should have indicated my merge. Now mind you, there was nowhere I could go except onto the autostrada. However, ever since that little lecture I've signaled even my most basic moves.
I consider it courteous. I am not on the road by myself. I recognize that. I wish everyone did.
I also wish American police would pull people over for not signaling. But I guess they have other, more pressing problems.
This morning (while waiting for yet another, as it turned out, non-signaling driver), I thought that even if stopping climate change or eradicating war may be too complicated for us mere mortals, at least we could all get along better simply by using our turn signals. In researching graphics to go with this post, I found several bumper stickers that read, "Forget about world peace. Visualize using your turn signal!" Unfortunately, putting that message on a rear bumper doesn't do much good.
I have one other pet peeve, but it's idiosyncratic and I manage to get over it pretty easily. (I'm sure you'll read about it one of these days.) This turn signal thing, though: to get pissed off every day because there are so many inconsiderate drivers out there? It wears me out.