I don't know, I just feel like in the past couple of months, I've seen a lot of jerks on the road who either:
- neglect to use their turn signals when turning, which is rude to the people behind you as well as any people who may be turning from the road you're turning onto, or
- neglect to use their turn signals when changing lanes.
But anyway, like, turn signals are a thing so that you can be courteous to other drivers. It's polite to let people know that you're planning on turning and/or changing lanes.
Actually, I'm not even going to argue about using your turn signals when turning, because that's literally what they're named after. If you don't use your turn signals for turning, you're completely useless to me.
But people who misuse their turn signals when changing lanes make me really angry too, and I think this probably applies to many more people.
Here's the thing. You can't just feel free to change lanes whenever you feel like it. If you have plenty of room, that's completely different and I'm not talking about that. I still use my turn signal unless the road is like, almost completely clear, but it's whatever. But when you're changing lanes relatively close to someone, you'd better turn your turn signal on! I should be able to grant or deny permission for you to get in front of me.
With that said, the thing that bothers me the absolute most is turning your turn signal on when you're already changing lanes. Yeah, buddy. I got it, you're coming over. I can see that because you're already halfway in one lane and halfway in my lane, usually way too close to me.