This window on the train in South Korea suddenly changes color: But why

This window on the train in Korea suddenly changes color. But why? Just as the scenery is about to change, the window suddenly becomes opaque. These windows are made of smart glass that adjusts its transparency with voltage. At first, you might think the train is passing by a government facility that shouldn’t be exposed. But actually, as the train passes very close to residential areas, these windows are there to protect the privacy of residents.

Видео This window on the train in South Korea suddenly changes color: But why канала Ethan Blake