This depends massively on the budget, the publishing company, and the author.
I started off in a publishing company as an editor of cookbooks. There's different levels of editor, ones that will check spelling, ones that will check sense and language, someone to advice on the contents. My task was to read the recipes provided and make "alternatives" to pad out the recipe count.
Often my job was to write extra recipes. For example, the book might advertise it contains 100 recipes. The author might be paid for 50. Then, because it was cheaper than developing 50 more new unique recipes, I'd be paid to do the rest, things like vegetarian versions where I'd just say "substitute the bacon for a big mushroom". It was really scammy and made me very discerning about cookbooks. Always avoid ones by people (like Jack) who churn out hundreds in a short amount of time, they will not have time to develop and test them all. These almost always don't pay for the spell check and the grammar etc, they might get a cursory check to make sure there's nothing inappropriate like anything that could be dangerous or damaging but the rest will be largely left intact.
Sometimes my job would be to read the recipes and make sure we had photos that matched each step and a total idiot could understand it. These ones would cost a lot. There's agencies that have recipe developers who'll have huge stacks of recipes you can buy off them, they'd hire their own people to take photos and sell them as a bundle. Sometimes places will buy these to make their own, or they'll sell them to bulk out a "celebrity" book.
I was so put off by the industry I trained as a nutritionist, and wrote a few of my own books. I completely agree that hard copy books are a bit of a waste of money (I do actually own far too many but I love them and get them as gifts), and so my books are cheap pdfs only. I actually make a lovely stew/casserole thing with (veggie) sausages, chard, and baked beans. I published it in a cookbook. Can I expect a cease and desist from Jack soon?