Mithrandir already gave some great examples. I would add a couple more - both Communist and Nationalist Chinese factions used Japanese equipment during and after the Chinese Civil War, despite the symbolism carried by it. They were, after all, useful weapons, some quite modern and capable (the Ki-84 fighters, for example).

The United States Colonial Army used the same uniforms during and after the American War of Independence that were issued by the British Empire. Why? Again, because it was not only practical, it was necessary to do so.

Now, Star Wars being a movie I understand why they went with the “visual aesthetic inheritance” for the good/evil factions, even though the Resistance using old Imperial equipment would have been a radical and fun thing to see.

What I do not get is why is the FO so clean and flashy, while the Resistance is all rag-tag? Alright, keep the design aesthetic but couldn’t we actually reverse the theme and have the good guys be shiny and well equipped, while the FO soldiers being the grizzled but stoic making do with worn-out, dirty and scrapped together equipment? TIE-Fighters actually looking like the Rebel fighters in ANH, dirty, worn-out, and having personal insignia as each one is precious and kept to its pilot; stormtroopers being more varied as their armor doesn’t get issued on time after repairs are needed and they have all kind of field-mods, being dirtier and scratched…

Would have been cool. 😕