As much as I hate to say it, The Germans got us beat on this one. When they get to traffic and lanes are merging they MUST file into the single lane like a zipper or they will be ticketed if caught not letting the next person get in front of them.
On another note, driving has gotten pretty bad in the recent past. The lack of use of signals is just unbelievable. That is one thing that should be enforced. They are for signalling your intentions and they are not optional. It doesn't matter if you are going 100 or 10 mph. Because someone around you is not going the same speed and doesn't know your intentions unless you signal them.
Please, please... Don't even get me started on the cell phone drivers. I do answer mine and ask them to hold on until I can pull over or call me back.
The other big one is people not turning on their headlights when it is getting dark and in the fog. There is just a certain percentage of people that refuse to understand the benefits of headlights in those situations. They figure that if they can see then the lights are not needed. WRONG!!! OK, rant over. I feel much better now.
Maneuvering without signalling is bad; signalling without maneuvering is probably even worse.