If it was one truck who didn't read a sign that everyone else caught, then yeah, you might have a point.
But it's multiple different people, repeatedly doing the same thing. That is the sign of a design flaw. You can't change something standard, put a sticker on it, and expect people to adapt.
Imagine someone built a car where the brake was in the middle of the steering wheel where the horn usually is, and the horn was on the floor where the brake normally is. You warn the driver, put a sign on it, and then send someone out to go drive across the country.
Do you really think nothing bad will come of this?