Camouflage uniforms have sometimes been issued in limited amounts, especially during the World Wars. In some cases, they were chosen for practical reasons. Recon troops and others who needed legitimately better concealment were given them. One interesting case is the US only really deploying camouflage uniforms in the Pacific theater in WWII, as the Germans loved camo, and thus using them in Europe caused too much confusion. Another one is how a lot of armies that previously used the classic M81 Woodland have updated their uniforms, since the ubiquity of that pattern has made it very easy for enemies to make disguises.
But there have also been cultural reasons, for lack of a better term. And not just bandwagoning like the infamous American “every service stomps into a digital camo pattern” experience in the 2000s. I’ve heard that the postwar Bundeswehr was slow to adopt camouflage uniforms because of their association with the Third Reich. And in places like Saddam Hussein’s Iraq, camouflage has been reserved for elite units as a sort of status symbol. There’s also police forces adopting blue and/or gray pseudo-camouflage to show a sort of “military power”.
This aspect of camouflage uniforms is both ironic (something intended to blend in is chosen because of its looks) and interesting to me. As is the reputation that seemingly neutral camo patterns develop based on who uses them.