What do flags from various countries have the same color schemes? Why not the colores orange, pink, magenta, turquoise, etc.?

Magenta is a synthetic colour created in the 19th century and is too modem for most countries. There are flags with orange like Ireland. And Kazakhstan has a sort of turquoise colour in it. I've never seen pink in one though. Red White and blue like UK flag is pretty common and boring. And given that it's the same colours as the USA flag we ought to change it so nobody connects us with them.