They can’t be bothered?
They’re too damn lazy to flick that little lever all the time?
They can’t have “the man” telling them what to do?
They already have a cellphone in one hand?
They’re stupid?
Turn signals are just so…old school?
I’m curious to read what Dopers have to say on this motorway mystery.
I can’t be bothered unless I am reasonably certain another is likely to be in a position to rely on the signal
Are you serious, Bearflag?
Yes. If I’m the only one around, why bother?
And there you go, the most likely reason of all.
Laziness.
“I can’t be bothered”.
I’ve asked this of my husband. He says that he never thinks to do it. I don’t know if he didn’t take Driver’s Ed or what. It’s second nature to me - especially on our multi-lane roads.
Sometimes I think it’s because he grew up on a dairy farm. There wasn’t much traffic here, back then.
What I see more often than people neglecting to use signals at all is people using them to announce what they’re already doing. Not very helpful, since I can already see them changing lanes / turning.
If you ask the average Southern California driver, (s)he’ll probably tell you it’s because (s)he’s the only person on the road.
Gaaah! It is the person you didn’t know was there that most needs you to use the flipping signal.
But to the OP, the number one reason people don’t use them is just to piss ME off.
Nah, I grew up on a dairy farm and we were taught to be extremely safe. Including such things notifying everyone in your vicinity of your vehicle moving intentions.
This comes from hearing, from a very young age, things such as, “if you reach in there, it will tear your arm off.”
I suspect that people don’t use their turn signal because of laziness. I have been criticised, however, for using my signal when no other vehicles were around. So, maybe, part of it is because people don’t want to come off as a prude and then be mocked and ridiculed.
Oh well. Now he has no excuse !!
Let’s pretend I’m on a two way street with one lane in each direction. I’m approaching a “T” intersection where I can turn right or go straight through. I intend to turn right. There is nobody behind me, nobody approaching, no pedestrians standing on the street corners, no cars on the other road that dead ends at the “T” intersection, and I have a green light.
Where else could this person be whom I didn’t know was there? Maybe an airplane will land at my intersection? 
The time and effort you spent typing a post to justify your laziness is probably equivalent to using your turn signal thirty times. I don’t get it. Is it really such a hardship?
Turn signals are a sign of weakness. Didn’t you know?
Not really, but why do a useless act when I could more easily not do it?
So, what percent of the turns you make are made with no one around?
When I’m walking my dog, I’ll cross a street parallel to a car coming. If the car decides to turn without a signal, I’ll be sure to be in the ped xing and walk as slowly as possible. If the car does have a turn signal on before arriving at the intersection, I’ll wait. I only walk if there is no evidence that the car is turning, btw.
I always, always use mine, by force of habit, even if I don’t think anyone is there.
Moving thread from IMHO to The BBQ Pit.
In Southern California, Mexico and places in New York, if you use your turn signal to indicate you wish to change lanes, someone will speed up to cut you off.
Kathy
Not if the time between the signal and the change can be measured in milliseconds. 
The only thing I have against turn signals is the guy who has run up in a lane with a lot of space to get to the point where his lane stops, and then uses the turn signal to try to push into the slower lane now moving faster. (No merge coming.) Too bad, bub.
Consistent with my previous post, if there is a reasonable risk of my failing to see another driver (e.g., in my blind spot), then I signal.
If a cop is hiding, then that’s my problem and nobody else’s.
I don’t think it’s anyone else’s place to say what my habits should be.
I don’t think I’m better than anyone else, nor have I claimed to be. I also don’t understand the venom, as I thought we were having a civil discussion.