Physical Danger
Glaziers work on construction sites, lift heavy things, use heavy equipment, and even work high off the ground. Sometimes, up to a few hundred feet high. Danger? Yes there is danger involved in being a glazier. That's why some jobs come with hazardous duty pay and why on the job training is key.
It doesn't take that long to learn how to score glass, snap it along the score line, and polish the edges. What does take a while is seeing a variety of work situations, learning what the pitfalls are, and most importantly, how to protect yourself. Shortcuts are for your keyboard; never for safety measures.