Excellent example of safe design for the careless user is the garden strimmer. The cutting tool on these is usually made from nylon thread. The properties pf this material mean that it will effectively cut through grass and weeds, but that it will not cut through human skin.
The context in which some products are used can make them potential distracters from other possibly more important tasks. A particularly pertinent example of such a product is the car stereo. Operation of this product is a potential distracter from a far more important and safety-critical task that of driving the car. This might mean that the demands on the design of a car stereo in terms of usability will be considerably more exacting than the demands on designing a stereo , it might be accepted that provided people could learn how to use the main functions within a reasonable period of time, then the stereo would not simply be about whether people could use the stereo, but also about the level of distraction that its use had on driving.