Free parking is the default. Why would they need to complicate the message by adding that?

But that is cultural. This problem isn't limited to parking signs. For example, see http://port-orange.us/wp-content/uploads/2014/07/No_U_Turn.j... or https://janiceheck.files.wordpress.com/2014/04/ped-xing.jpg

I cannot imagine there can be people with a driver's license who do not understand those signs, yet can understand the text below it, and have time to read them while driving by at 40 mph.

I would leave out the 'helpful' text or if that's legally problematic, think before ordering the sign, and get a single sign that includes the label. That's cheaper, and makes the world look a bit nicer (does anybody have statistics on # of traffics signs per capita or per mile of road? I expect the USA to score high in both)

> Free parking is the default

But how would someone visiting/freshly immigrating there know that if it's not displayed somewhere?

How would he (s)he know to stop on red lights, not drink and drive, stop for pedestrians at crosswalks, give right of way to traffic from the right, drive on the right side of the way, indicate change of direction, not drive after drinking alcohol, etc?

Before you know it, the street is full of signs, and drivers haven't time left to attend to the traffic (actually, that might explain the relatively high number of traffic deaths in the USA)

When you visit another country and intend to drive a car, you have to spend some time studying the local traffic rules.

Also, AFAIK, free parking is the default all over the world.

Well, my time in Holland was the first time driving outside of North America. I turned right against red signals a few times until I had an European coworker in the car.

Until the parking signs were explained to me, I had assumed these meant no parking except during these times, and that everyone parking in the spot should buy parking permission from the machine.