If you work with a bunch of people who commute a long way into work and do not cook and you want to fit in with your coworkers. Generally I would bring something in but be available for lunch because it's nice if you like your coworkers to hang out outside of work sometimes. This goes against my instincts for frugality. This was long before company provided lunches and the like, though, I've worked at places back then that were large enough to have on site cafeterias and we still went out most of the time. Also might be an age thing because we were all in our 20's and the veterans at those companies almost universally brought in their lunch.

Cooking quickly becomes a bad time/value proposition when you're cooking for one, so that's part of the equation. And some of us value the enjoyment of many good meals over say, having a newer car. I planned to include daily lunches in my budget before I even left college (couldn't afford it at the time). I don't regret it one bit.

I used to cycle commute everyday and would vary the route from 12-60kms. Where I live is very hot in summer and wet in winter. So a shower was needed when I arrived at work. I preferred to not carry a backpack or have a pannier on my bike, so every fortnight I would drive to work and drop off work clothes for the next couple of weeks.

This also meant I would go out for lunch each day as I didn't want to carry food with me on my commute. The cost savings of riding to work vs driving and paying for parking meant I was ahead. If I took public transport and brought lunch from home it would have worked out slightly cheaper but taken 30mins longer each way.

Sure I could have carried lunch with me on my cycle commute but and saved more money, but then I would have enjoyed the ride less. I figure I would still be ahead compared to people who don't cycle and pay for gym classes/memberships.

Food available at the office or paid enough to be able to do so. Very common in the major SV companies.

When I was in grad school, there was a huge collection of food carts right outside the building. You could get a large meal of virtually any cuisine for $5-6.

As a single person who liked variety and worked a lot, it was a slam dunk: fast, tasty, and relatively cheap.

Many large companies have a cafeteria on site.