For a street legal auto, a glass windshield is a must. Tempered safety glass laminate is required to be used as a windshield for any car that is to be used on the street. This is mostly because the alternatives that are used in racing, such as Lexan and Plexiglas, scratch too easily. These scratches would, quite quickly. Decrease the visibility through the windshield. Regular glass has a much higher resistance to scratching and hazing. Even if it isn’t as impact resistant as the plastic alternatives used in racing vehicles. PPG is the largest supplier of automotive glass in the United States.
For more info, see Common Causes of a Windshield Chip