I think they didnīt get cause right. Those stickers usually reflect a certain attitude. This attitude often leads to a more aggressive way of driving. The more aggressive way and the lack of gestures of apology (even if they are made they wonīt be seen) leads to the phenomenon called road rage.
However itīs wise to keep some distance between you and an individual that thinks itīs cool to offend others just for the sake of it.
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If it isnīt broken, it doesnīt have enough features yet.