If they truely were yellow flags, that means people aren't paying attention, and are doing stupid things.
Like other folks said, If it's a white flag only, or a yellow/red, that's NOT a no-passing flag. It's up to each driver to decide if it's safe to pass or not. Of course, some people always have worse judgement than others.
Myself, i usually err on the side of caution, but others? not always so much. I'm not condoning it, just saying that everybody's definition of "safe to pass" varies greatly.
Remember, on the highway, anyone going faster than you is a maniac, and anyone going slower is an idiot!
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