Why have so many countries chosen red/white/blue for their nations' flags?

Those 3 colors are pretty catchy, but when it comes to the USA, they see freedom, and a better chance at life.

haha, good question.

Interesting point about symbols here. For the red, white and blue of the French or the Russian, say, what do you suppose their flags mean to their citizens? Travelling around the globe is fascinating. I can promise you that the US (always the biggest on branding by far) has more flags on public display than any of the other 27 countries I’ve visited - a LOT more, in Washington alone there are probably more national flags flying than you’d see in an entire other country. The obvious exception would probably be China, where the many red flags are daily reminders of the benefits of the state. Politically, in both US and China, the flag is a tool of statecraft (the prominent use flags by Hitler is an older example). By contrast, the European flag is not that prominent in most of the member states except for the ones which are the main economic drivers or those with HQs. Even in London, you have to look hard to find a UK flag. The recent revival of the English flag (red cross, white background) has been football-driven but sales collapsed as soon as we fell out of the world cup! You still see a lot more of those than UK flags tho, mostly dangling from teenage bedroom windows! A nation’s use of flags tells you a lot about its values.

Someone just told me it’s because red and blue were the only two pigments that were available in economic quantities at the time (18-19th century) and it was not until paint technology improved that orange, green, etc became available. Sounds plausible but it could be a guess - has anyone seen a factual article?