In reality also many drivers do not react to your blinkers. That's sad but is realistic.
To be serious: I would like to see those reactions in R&R, too. SCS games show how good traffic works. There the cars drive behind you to let you change the lane.
Changing so much lanes in that way usually happens when the traffic cars or drivers recognize that they are on a lane that goes to a city they don't want to drive to. So they suddenly change the lane to get to the right city.
Not very realistic and really dangerous, but it's always a good chance to test my truck horn.