Just to go to the other side of the argument, we have some very short slip roads on a dual carriageway here and the amount of cars that just join blindly at speed is scary, seen it loads of times where lorries have had to dive in to lane 2.
This x100. Daily life for us out there. Having to slam on the brakes or swerve in behind a car in lane 2 to avoid some moron blindly joining from a slip road is a daily occurrence. From our point of view we're always checking for space to 'escape' into lane 2 on approach to an on slip, but some people just shouldn't be on the road clearly. The amount of times I've been beeped at by people joining in heavy traffic forcefully when there's no possible gap is astounding.