This is exactly what it is. Nothing stopping these local highway patrol and safety departments from erecting electronic signs on the side of the highway for all their cute messages.
It’s that they’re using the big electronic ones that are overhead while driving which should be uniformly easy to understand, simple, and official.
Basically, if there’s a message on a sign above the actual road and it takes you more than a second to understand what it’s trying to say, it needs to be revamped.