Price: Within reason, who cares? I don't have a wife or kids or any obligations really. What good is a six figure salary if I have to micromanage what I'm spending on food?
Calories: Diets don't work, so who cares? If the meal is too big to finish then I'll take half home for dinner, like I did today.
Time: IDK if you eat a cold turkey sandwich for lunch every single day or what, but it would probably take me 30-60 minutes to make the things I often eat for lunch, if I even had the ingredients. I don't have the benefit of hours of kitchen prep before the restaurant opens.
Getting away: This is a big part of it actually. Not just leaving my desk, but leaving the office entirely. Walking around the downtown, remembering what it's like to be a human being in the sunlight.
I realize these answers may not match your lifestyle but I'm just trying to give the insight you asked for, from a person who does this.