Breakability, among others, I suspect. I've never cooked commercially, but I did work at Cinnabon long enough ago that we made the rolls out of things that were identifiably ingredients. All the staff cups were plastic because things get moving pretty quick on a busy day.
The one Christmas Eve I worked in college was bananas. We had both ovens running (doesn't happen outside the holiday season) and were putting pans in and taking them out about as fast as we could make rolls and proof them.
I think it's that, but just as much that glass glasses are unitaskers, and delis are some of the most multifunctional things you can stock in your kitchen.
Well I don't think residential kitchens are as chaotic as a commercial kitchen, so sure drinking out of a non breaking container is probably a good idea (glass breakage is a pita there).
However most people (I assume on HN) are not line cooks and do not work in commercial kitchens. I drink out of glass (don't want plasticy taste) and use glass to store leftover food.
Here's one: "There's a reason most line cooks drink out a deli rather than read NIH" [0] :)
As previously mentioned, whether one thinks using glass is worth it is a personal preference.
I store leftovers in deli cups. I usually wash them afterwards. A rigid plastic deli has about as much plastic as a freezer bag, but by the time you've reused a deli once, you've crushed the freezer bag in efficiency, and the median reuse count of one of my delis is probably double-digits. Meanwhile, if I need to clean my fridge out fast, I can just check the entire deli in 2 seconds. Do that with a glass container.
You do you, but if you buy prepared food, be aware that no part of the supply chain for that food is fastidious about plastic the way you are.
