Colonial Pedestrian Signals?

I've just made a startling discovery: the pedestrian signals in the United States appear to be relics of - or at the very least echo - the country's colonial past*.

Let's start with the "stop" sign, known locally as the "don't walk" signal. In most places on this increasingly standardised planet, this depicts a standing man in red. Here in the New World, although the universal danger or warning colour is retained, the man is replaced by a hand clearly making the classic Red Indian "how!" greeting sign normally used in western culture to indicate an order to stop.

The "go" sign, by contrast, features the globally typical "walking man", though here too there is a twist: he's not green, as is common elsewhere, but white.

Combine the two and you have what could be interpreted as: "Palefaces: You are free to move about as you please. Redskins: Hello. Stay where you are".

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* This does not apply to traffic lights, which conform to the usual red-green pattern.