About half of my coworkers buy food at a restaurant every day for lunch. I can’t speak for the rest of the meals since I grew up in a frugal family and my wife and I are fairly frugal. We still eat out more than I like, which is about 4-5x/month, and I think a lot of people eat out like for half or more of meals.
And the worst part is, people who eat out a ton often go to fast food, which is incredibly unhealthy. We go to fast food maybe once a month, the rest are to more interesting restaurants.
I think the average American will have breakfast cereal or a muffin or donut (i.e. with their coffee) for breakfast, then fast food for lunch, and either fast food or a prepared meal from the grocery store (e.g. freezer section) for dinner. Cooking is a rare thing on weekends or even guests come over, if it happens at all.
Especially in large cities like New York, where there's an endless amount of very good food, most apartment kitchens are very small, and many people make a pretty decent amount of money. plenty of people cook very little or not at all.