Quite the tell wrote:
You're missing the point. If you don't mess up you won't interrupt others around you. I agree, it's rude if you just barge in without signaling, but the point is you get in the lane when the space is open, therefore not interrupting anyone.
Let me put it this way: do you signal when you're the only person on the road? Probably not, unless it's a force of habit because there is nobody you need to signal to, right? So if you're driving with the proper amount of forethought there is no need to signal 90% of the time you are taught to in driving school.
You understand that there are a lot of places where this will never happen, right? Try driving form Chinatown into the Holland Tunnel while only ever moving over when space is available, and report back to us on how many days it takes you to get out of the city.