I wonder this same thing when I’ve been routed completely asinine ways off interstates at night when traffic appears calm. I always have to play the game of “is there horrendous traffic ahead from night paving / accident, or am I being conscripted as a traffic sensor robot?”

Government data sources can input real time data into Google Maps [1]. So, it's more likely than not that local police or state DoT is behind that.

[1] https://contentpartners.maps.google.com/