The cockpits of the planes,vacuum cleaners,home appliances,interior of the old cars literally everywhere
I suspect that blue and red paints were ones of the few things that managed to manufacture in high quantity and reasonable quality. Yellow and green colors sure looked dirty. White might look fine originally but soon became dirty from an actual dirt. If they would paint their planes red it would be a. silly b. too in your face as export of the revolution when such plane would land in other countries It leaves them with blue color only. They had red flag painted on the tail of their planes though.
It's just a cultural illusion ie. the color 'blue' is popular in Russia<and many countries including the USA but you are just seeing its use in another cultural context. Russian airborne troops were called 'Blue Berets'. Early NKVD/Cheka forces in the early Stalin era wore blue berets... There's a blue/camo used by troops in Russia...BUT it's only noticable really because one is comparing one culture to another ie. why do US police wear dark blue? Why are there so many green uniforms and green berets? Look more closely into Russian things ie. there's a great variety of colors...but blue is a popular color! I hear RED has been popular too. LOL
