In all fairness, examples and context usually would push them out past magazine length. (It's also true that, based on the complaints here about things like recipe embellishments, I'm probably more tolerant than some.)

That said, many/most are padded out. In general, you can't publish a book unless it's 250 pages or so. The economics for publishers apparently just don't work out. Fairly or not, a lot of people at least subconsciously buy by the pound. They're not going to pay $20 for a 50 page book in general.