My DD wanted a nando's and we were seated near the semi open kitchen. There was a grill for the chicken but the salad came preshredded in huge bags and all the sides, corn, rice, potatoes etc was frozen in bowls that were put in the microwave. Known as "ping" cookery in Hong Kong as so many Chinese eateries use it. If your meal comes suspiciously quickly out of the kitchen this is how it has been reheated.
I saw a documentary about restaurants. They filmed at the Rainforest Cafe in London. All the food was cooked then meticulously weighed and put into 1 portion plastic bags, so each person would get exactly the same amount of spaghetti and bolgnaise sauce as another. Some was fridged and others frozen to be used later.The chef argued it was for "fairness"
In the defunct Jamie Oliver Italian chain nearly everything was actually prepared offsite - frozen ( lasagne's, rottolo, desserts etc) or prepacked and just put on a platter to look nice such as charcuterie, olives - no real skill involved.
Gordon Ramsey was also "caught out" using an off site "dark" kitchen in an industrial estate to cook a lot of dishes supplying a few of his eateries, some even had "open kitchen/chef's tables" . Some quick food was cooked fresh onsite but he argued it was fine to cook the "slow" dishes such as lamb shank off site as they took many hours to prepare and to then deliver them around the place to be "boiled in the bag" aka sous vide eheated
It's hard to get properly qualified chefs as the wages are so low and the hours so long with often a useless gap in the late afternoon/early evening. Many places want cheap labour not skill.