My OH is a Head Chef. He makes everything from scratch. But- it costs.
The only thing he doesn't make from scratch is coeliac friendly bread. If there is a coeliac eating, another part of the kitchen is cleaned down and a chef will prep everything in there away from main kitchen to prevent cross contamination.
It costs because of a) time b) fresh ingredients c) cooking in smaller quantity
However, he gets loads of customers who have dietary requirements because it is made fresh. So often guests will call ahead and say I am allergic to this, this and this, can you accommodate this? Almost all of the time he can make an adjustment so he can. But again, this costs in time and effort. And the price of gluten free flour would make you weep.
But yes- and most puddings in chain pubs are also mass produced. Think pre-cut gateaux type things with 45 portions etc.
However, there are some very well thought of, talented chefs working as development chefs for these chains. It's often cheaper because of economy of scale and buying power- it doesn't always have to be awful, poor quality food.
He was doing some agency work a few years ago to earn some extra holiday cash- one place he went to was selling the Heinz tins of Macaroni cheese as Mac N Cheese. It was dirty as well, so he didn't go back there.
But yes, Ping Ping Chefs are a thing.