Unshielded lights create glare. Glare decreases visibility. Unshielded lights pre expensive. 35-70916 is wasted by going up in space. Wasted energy contributes to unnecessary global pollution.
Unshielded lights cause light trespass into one's own home and violate privacy in others'.
Uplight causes sky glow and obliterates stars, meteors, and the northern lights. As a result, astronomical deep-space study is severely hampered and we can no longer see the beautiful night sky. The best lighting fixtures put light where it is needed. Notice haw these light fixtures throw light every where. One person's security light can become another person's prison light.