Whenever I'm tempted to get angry at someone else for their behavior on the road, I try to think if there might be a reason for it. The shoulder might look good from the view inside a car, but maybe there's some glass, a drainage grate, or other hazardous thing that seems perfectly fine from inside a larger vehicle. For that reason, I don't tend to express any displeasure unless the behavior is outright dangerous.
__________________
It's like riding a bicycle