This is the real reason. People aren’t incapable or put out by having to use the turn signals, they are choosing not to signal precisely because it reveals intent, and they are afraid of revealing intent. (Same is often true in many other social situations and at work!) I know I’ve done this myself in the past, and I know other people who will admit it. Fear of being cut off, fear of having someone not let you in, general fear of someone using your intent against you rather than accommodate you.

I think we need to figure out how to teach not just that signaling intent is safer, but that it works and people will accommodate a signal far more often than not. We also need to learn as drivers to respect other’s intent, that when a signal is on and it’s close but they have room, it doesn’t mean accelerate to close the gap, but that we should let them. Being nice is how we get others to be nice back.