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.