Re your comment about more wrinkles in fabric from certain sources, one reason for that can be store personnel being required (or choosing) to measure the amount on each bolt received to verify quantity. If they do not put it back on carefully, there can be many more wrinkles.
Also I've discovered that if I don't fold my fabric carefully when putting it away it can gain more wrinkles that way too.
And then some fabrics just are more prone to wrinkles than others. I think it may have something to do with the manufacturing process and whether or not a wrinkle resistant finish is added.