sign language

there's this electronic sign on the side of the ring road highway. when the roads are icy, the sign says "drive slow--icy roads".
when all the cars see this sign, they slam on their brakes. last week, a truck movin at 120 km/h slammed on his brakes at the sign, slowing to a speed of about 60 km/h, forcing me to slam on my brakes. on the icy roads.
this is lame. i'm going to die because of a warning sign.
this same sign often says, "don't drink and drive". it's in the middle of the highway. i think, by that point, if you are drinking and driving, it's a little too late to do anything about it. this sign should be something you see right outside the bar, not halfway home.
the same sign warns of fog (when it's foggy) and snow (when it's snowy).
what are they gonna do in the summer when we're not getting precipitation? will the sign say, "it's sunny out, drive fast"?
maybe, instead of sending out birthday cards this year, i'll get in contact with the sign people and get them to write neat things like, "HAPPY BIRTHDAY [friend's name]. FROM SUZY"