Maybe they're just wearing cheaper quality uniforms, but the cotton looks to be of very, very bad quality, and they look way too clean. Almost like haloween costumes. Also, from what I've seen in reenectment videos, not many people actually seen to be very passionate, or even good at their roles. I see a lot of smiles, leisurely marching, reloading and firing, and just a general feeling that hardly anyone is taking the event serously.
Now, I know that often this is just a fun time with friends, but if I were paying in the upper hundreds or thousands for my gear, and if there were a group of spectators like there often are, then I might want to put some effort into my acting.