The NCOWS group caters to the more authentically dressed and armed individuals, are are closer to a "reenactment" mentality than most SASS/ cowboy action shoots. There can be a difference in $$$$ too, as the more historically correct you want to go, the more $$$$ you'll likely have to invest.
There is a little piece in it for everyone if you are willing to work toward what you want and ignore the gamers and others that want to push personal agendas onto other shooters that just want to enjoy themselves at a pleasurable hobby.
Just try to find some like minded folks locally, and go shooting with them.
If you don't- just be a curmudgeon and have fun by yourself like some of the rest of us.
Maybe instead of "cowboy action" I'll suggest we have a "cowboy slow motion" match at the range...with pistol targets at 25 yards, and rifle targets at 50 and 70 yards- that'd throw a wrench in the works. It'd sure be interesting.