Doing this was a firing offense in my bar. Do it just one time and you’re fired on the spot.(Never had to fire anyone for that, happy to say.)
Glasses can and do chip. A sliver of glass in an ice bin is a disaster waiting to happen. And when you get busy, servers start taking shortcuts and you get hot glass from the Hobart because it doesn’t have time to cool down, which can cause cracking when the glass is chilled too quickly.
Glasses should always be filled with ice from a scoop, never dragged through the ice bin. I know that sound, and whenever I hear it at a bar or restaurant it sets my teeth on edge. And I’d guess that fewer than 5% of establishments follow the safety rule.