It's so funny. I still remember there's this ads on local radio described a scenario where a guy over cut lane without watching cars at the back and thus being screwed, although signal light is given. This scenario is actually a wonder, I think not only me but among a lot of us. Why is that? Well let me explain on it.
You see, as all the drivers know. Signal light is is used when one is trying to change lane and wish to get permission from cars on that lane in order to slow down and let this car pass through. Now, the problem is, the signal light is somehow very effective where..., the driver who wants to change lane, after confirmed that car on other destination lane is very far behind, turn on the signal and slowly move the car to different lane. But, however the car which is slowly behind on the other lane, saw the signal from this car, and immediately accelerate the car to speed up to the front so that this car is unable to move into the lane. While in the other hand, when the car just change lane without giving signal, the car at the back knows that it's too late and did nothing nor accelerate. What the heck? So the signal light is now actually used for car behind to give no permission to other car to change lane? My gosh...
Besides situation above, there are people who misused the signal light as well. How they do it? Different from scenery 1, they will not care whether the car on destination lane is far or close. They feel like want to change lane, turned on signal light, and straightly move in to the other lane, regardless on whether there's car very near on the other lane or not. This situation is like.., "whether you allow or not, I'm coming in." or "there's no space for me to move in, then slow down your car and make way."
After reading these scenario, you see. I seriously doubt what is the actual usage of a signal light. Should we use it?? Or should we not? Sigh..