Having previously worked in fast food as well as regular restaurants, most if not all fast food and major chain sit down restaurants get their vegetables pre cut from their distributors or other vendors. Nothing new there, even Boston Chicken (now Market) used to have their side dishes cooked in a central commissary and delivered a few times a day when the chain first started as Dunkin Donuts does with their donuts now. It reduced space needed at the stores as well as gave consistency of being the same quality if you visited different stores.

The restaurants who have their own chefs versus line cooks will cut their own as needed as these restaurants are more high end and individualized.