I think this is going to depend a LOT on the person, where they live, and their habits. But yes, it is a thing!
When I was 20-something, in DC, and in the Navy, I had the "latte habit". Not really. I didn't drink coffee.
Once I went from Ensign to LTJG (more money!) - I cooked less, and packed lunch less. My friends went to lunch, and so did I! I'd get a sandwich and a diet coke. The guy at the deli in the Crystal City underground saw me coming - he knew it was either a tuna sandwich or a Reuben. The guy at Moby Dick's knew I wanted a veggie wrap with no tomato.
That grew...into dinner and and beers after volleyball games. And a bagel on the way in, because I didn't feel like having cereal. My god, when we bought our house, I found a credit card statement from my last year in DC. $1000 a month, about $800 on that eating out. In 1996. Jeez.
And it still hasn't changed much. While I've reigned in the spending, and pack lunches now (I calculated that packing lunches saves us about $17k in 5 years)... sometimes, the kids want a smoothie. Or the husband wants a burger. Or we are tired and want to order pizza. Or I don't feel like packing my kid's lunch every day, only to have him not eat any of it. And it's okay to order a pizza, or grab a burger, or get a smoothie on Saturday as a treat. But the problem becomes that it turns into a "thing".
Then, next thing you know, Weds is burger night and Friday is sushi night.
Friday afternoon when school is out, let's go grab Fro-Yo!
Sunday morning, bright and sunny, how about brunch at that cute place on the beach!
It's easy to slide into these habits. We don't tend to slide into them as easy as others, but it still happens.
At my office, I have a friend who's "frugal". But he's an empty nester, buys lunch every day, and shops at Whole Foods.
I've got plenty of other coworkers who buy lunch 4-5 days a week. They get more variety that way and don't have to think about packing a lunch.
Another friend who takes a daily "walk" and gets an iced tea and lunch at SBUX.
Two other coworkers who get coffee at SBUX every afternoon.