Standard Assets have very specific controls. They're not very good and easy to recognize. I'm talking about, for example, motion smooting that SA controllers use. There's also headbobbing. Also, if your game is supposed to be controlled by a keyboard and a mouse and you code only that, controller would not work, or would work badly. SA are crossplatform. So the judges can just plug ina controller, or anything else, like a steering wheel and check if it work. If it does, the movement is smoothed badly, controlls are not very responsive, they may think this game is using SA. But they probably have other ways to check it. There's nothing to fear, if you don't use them. Have a good jam!