Well, theoretically you're correct. However, I used to own a sign company, and I can tell you that it was often very difficult convincing customers who owned commercial enterprises to purchase signs that were actually legible. They routinely specified parameters (colors, letter type, letter size, too many words, etc.) that were just not going to combine into something that could be read, and more to the point, read quickly. Or conversely, they wanted a giant telephone number, with the business name relegated to insignificance. And on and on.
In any case, a surprisingly large part of my job was educationg customers as to just what would have a chance of getting a message across. 'Course, when government bureaucrats were the customers, it was even worse - then the most important thing on the sign was often a long list of names of politicians and others who wanted some sort of public credit.
Yep. I've a bit of marketing background. Signs and headlines should never be more than seven words, and preferably a lot fewer. Too many words and they won't read it - or in this case, cause them to become dangers on the road.