It isn't a per-soldier thing. It's just pieces of fabric that are all cut differently. They aren't out there making sure one person has a specific pattern that matches every single one of their uniforms, and doesn't match someone else's.

I get the line of thinking, and I tend to agree that if they really wanted to, they could figure out a way to match the pattern of a uniform to the person if the person had published a picture of themselves wearing the article on something like Facebook.

But that's a big if. When I was in the military, I think I posted like one picture of me in camo and the resolution was so low that you probably didn't have enough detail to come to any conclusions.