CE certification requires factory inspection, why

CE certification needs no factory inspection, according to the product and based on the directive, if it is a general danger level of low products such as low-voltage electrical products, mechanical products, etc. is not required, if it is a medical device products pressure equipment products, construction materials, most of the products need to be factory inspection. Factory inspection is not factory inspection according to the product hazard level and based on the CE directive can not be generalized.